v  DEPARTMENT  OF   AGRICUL  I  URE 
DIVb  IMOLOGT     BULLETN 


THE  MEXICAN  COTTON  WILL  WEEVIL. 


PREPARED  UNDER  THE  DIRECTION*  OP  THE  ENTOMOLOGIST 


W.  I).  H INTER  and  \Y.  E.  HINDS. 


WASHINGTON: 

GOVKRN'M  E  N  T     PRINTING     OFFICE. 
I904. 


DIVISION  OF  ENTOMOLOGY. 

L.  O.  Howard,  Entomologist. 

C.  L.  Marlatt,  in  charge  of  experimental  field  work. 
F.  H.  Chittenden,  in  charge  of  breeding  experiments. 
A.  D.  Hopkins,  in  charge  of  forest  insect  investigations. 
Frank  Benton,  in  charge  of  apiculture. 

W.  D.  Hunter,  in  charge  of  cotton  boll  weevil  investigations. 
A.  L.  Quaintance,  in  charge  of  bollworm  investigations. 

D.  W.  Coquillett,  Th.  Pergande,  Nathan  Banks,  assistant  entomologists. 

E.  A.  Schwarz,  E.  S.  G.  Titus,  investigators. 

Miss  H.  A.  Kelly,  special  agent  in  silk  investigations. 

R.  S.  Clifton,  F.  C.  Pratt,  August  Busck,  Otto  Heidemann,  A.  N.  Caudell, 

J.  Kotinsky,  H.  S.  Barber,  assistants. 
W.  E.  Hinds,  W.  F.  Fiske,  G.  H.  Harris,  H.  E.  Burke,  A.  W.  Morrill,  J.  C. 

Crawford,  Jr.,  A.  A.  Girault,  C.  T.  Brues,  F.  C.  Bishopp,  Springer  Goes, 

C.  M.  Walker,  temporary  field  agents. 
Miss  L.  L.  Howenstein,  artist. 


Digitized  by  the  Internet  Archive 

in  2012  with  funding  from 

University  of  Florida,  George  A.  Smathers  Libraries  with  support  from  LYRASIS  and  the  Sloan  Foundation 


http://archive.org/details/mexbolOOunit 


Bui.  45,  Div.  of  Entomology,  U.  S.  Dept.  of  Agriculture. 


Plate  I. 


Developmental  Stages  and  Work  of  the  Boll  Weevil. 

Pig.  1.  Cotton  boll  weevil:  tig.  2,  weevil  feigning  death:  tig.  3,  two  eggs  and  feeding  excavation 
in  a  square;  fig.  4,  full-grown  larva:  tig.  5,  pupa,  ventral  view;  lii,--.  6,  pupa,  side  view:  figs.  7-9 
show  transformation  taking  place  within  squares:  fig.  7,  larva,  full  grown:  rig.  S,  pupa;  fig.  9, 
adult;  fig.  10,  weevils  feeding  on  boll:  rig.  11.  larva  developing  in  boll.  (Figs.  1-10,  natural 
size;  fig.  11,  two-thirds  natural  size.— Original. ) 


I  .  S.  DEPARTMENT  OF    AGRICULTURE 

DIVISION  OF  BHT0MOL0OT     BULLETW  No.  16. 


l..  o.  ii»>\\  \ i ; i ».  Entomolooiht. 


THE  MEXICAN  COTTON  BOLL  WEEVIL. 


PREPARED  UNDER  THE  DIRECTION  OF  THE   ENTOMOLOGIST 


BY 


W.  I).  HUNTER  and  W.  E.  HINDS. 


WASHINGTON: 

GOVERNMENT     PRINTING     OFFICE. 
I904. 


LETTER  OF  TRANSMITTAL 


U.  S.  Department  of  Agriculture, 

Division  of  Entomology, 
Washington,  D.  C,  February  20,  1904. 

Sir:  I  have  the  honor  to  transmit  herewith  for  publication  an 
account  of  the  Mexican  cotton  boll  weevil,  prepared  under  my  direc- 
tion by  Messrs.  TV.  D.  Hunter  and  W.  E.  Hinds,  special  field  agents 
of  this  Division.  Mr.  Hunter  has  been  engaged  for  three  years  in 
investigations  of  this  very  important  injurious  insect,  his  work  extend- 
ing all  through  the  infested  portions  of  Texas  and  to  some  extent  into 
Mexico.  Mr.  Hinds  for  two  years  has  been  devoting  his  whole  time 
to  this  subject,  having  been  stationed  for  the  most  part  at  Victoria, 
Tex. ,  in  charge  of  laboratory  work.  The  bulletin  as  a  whole  is  a 
remarkably  careful  and  complete  treatment  of  the  entomological 
aspects  of  the  investigation.  It  seems  to  me  as  complete  a  treatise  of 
the  life  history  of  a  single  species  as  has  ever  been  published.  The 
necessity  for  the  most  perfect  knowledge  of  eveiy  detail  of  the  habits 
of  this  great  enemy  to  the  cotton  crop  must  be  obvious,  since  only 
upon  such  perfect  knowledge  can  we  authoritatively  base  remedial 
work  and  can  we  authoritatively  indicate  the  uselessness  of  many  of 
the  remedies  proposed  by  ingenious  and  inventive  persons.  The  six- 
teen half-tone  and  other  plates  and  six  text  figures  are  an  essential 
part  of  the  report. 

I  recommend  the  publication  of  this  paper  as  Bulletin  No.  45  of 
this  Division. 

Respectfully,  L.  ().  Howard, 

Entomologist. 

Hon.  James  Wilson, 

Secretary  of  Agriculture. 


PR  EFACE. 


The  .Mexican  cotton  1><>I1  weevil  (Anthonomus grandis  Boh.)  has  fche 
unique  record  of  developing  in  less  than  twenty  years  from  a  most 
obscure  species  to  undoubtedly  one  of  the  most  important  economic- 
ally in  the  world.  It  was  first  brought  to  the  attention  of  the  Divi- 
sion of  Entomology  as  an  enemy  of  cotton  in  Texas  in  L894.  Before 
it  had  invaded  more  than  half  a  dozen  counties  in  the  oxt  reme  southern 
portion  of  Texas  several  entomologists  were  sent  to  the  region  in  con- 
nection with  this  work.  Enough  was  soon  discovered  to  indicate  the 
mosl  feasible  plans  for  avoiding  damage  by  the  pest.  These  original 
plans,  based  upon  investigations  of  the  life  history  of  the  insect,  with 
modifications,  for  the  most  part  due  to  climatic  conditions  in  regions 
quite  dissimilar  to  the  lower  portion  of  Texas,  are  still  the  basis  for 
all  that  is  known  in  combating  the  pest.  However,  at  that  time  it 
was  necessary  to  pay  particular  attention  to  the  immediate  economic 
phases  of  the  problem,  and  a  detailed  study  of  the  habits  of  the  insect 
was  impossible.  In  1902,  by  the  aid  of  a  special  appropriation  by 
Congress,  it  became  possible  to  establish  a  complete  field  laboratory 
in  the  portion  of  Texas  in  which  the  weevil  had  been  known  to  exist 
at  that  time  for  about  eight  years,  where  a  careful  investigation  could 
be  conducted  regarding  the  points  in  the  life  history  of  the  pest  that 
offered  even  remote  chances  of  suggesting  means  of  avoiding  damage. 
The  results  of  the  work  at  this  laboratory  that  have  been  of  more 
immediate  economic  bearing  have  already  been  published  in  farmers' 
bulletins  of  this  Department.  However,  as  will  be  seen  from  the  fol- 
lowing pages,  a  very  large  mass  of  information  concerning  all  the 
habits  of  the  boll  weevil  has  been  accumulated.  Not  only  on  account 
of  the  great  economic  importance  of  the  problem  and  the  demand  for 
information  from  numerous  quarters  concerning  the  biology  of  the 
pest,  but  also  on  account  of  the  fact  that  the  methods  followed  in,  this 
work  have  been  to  some  extent  original,  and  may  be  of  use  in  con- 
nection with  the  investigation  of  other  insects,  it  is  thought  advisable 
to  publish  a  great  number  of  the  observations  that  have  been  made. 

The  historical  and  economic  features,  to  which  reference  has  been 
made  elsewhere  in  the  publications  of  the  Division,  are  included  to 
bring  together  in  convenient  form  practically  all  that  is  known  regard- 

3 


ing  the  species.  Much  information  obtained  by  the  earlier  investi- 
gators of  the  Division  of  Entomology,  Dr.  L.  ().  Howard,  Mr.  C.  L. 
Marlatt,  Mr.  C.  II.  T.  Townsend,  and  Mr.  E.  A.  Schwarz,  has  been 
used.  On  account  of  the  painstaking  character  of  the  work  of  Mr. 
Schwarz,  and  liis  intimate  knowledge  of  related  species,  his  reports, 
largely  unpublished,  have  been  found  especially  valuable.  In  pre- 
senting this  work  the  authors  have  taken  care  to  state  fully  the  data 
furnishing  the  basis  for  the  various  conclusions.  Under  each  impor- 
tant heading  will  be  found,  first,  a  description  of  the  methods  and 
apparatus  employed;  second,  a  full  and  in  many  cases  tabular  state- 
ment of  observations;  third,  the  obvious  conclusions.  Care  has  con- 
stantly been  exercised  to  avoid  errors  likely  to  result  from  artificial 
conditions  in  the  laboratory.  A  large  part  of  the  work  of  the  past 
year  was  in  ascertaining  how  closely  laboratory  results  corresponded 
to  the  actual  conditions  in  the  field.  The  writers  have  on  many  occa- 
sions been  surprised  to  discover  how  close  the  correspondence  is,  and 
consider  that  the  demonstration  on  a  large  scale  of  the  possibility  of 
accurately  determining  the  details  of  the  life  history  and  habits  of  an 
insect  by  laboratoiy  investigations  is  by  no  means  the  least  important 
of  the  results  of  the  investigation. 

The  laboratory  work  which  has  led  to  this  paper  was  planned  origi- 
nally by  the  senior  author,  who  has  also  supervised  the  later  develop- 
ments of  it.  However,  practically  all  the  labor  of  conducting  the 
experiments  and  observations  lias  devolved  upon  the  junior  author, 
who  has  suggested  from  time  to  time  man}7  important  modifications  of 
the  original  plan.  Specifically,  all  of  the  bulletin  except  the  first  por- 
tion, dealing  with  historical  matters,  the  destructiveness  of  the  pest, 
and  the  prospects,  and  the  last  portion,  dealing  with  methods  of  com- 
bating it,  was  written  by  the  junior  author,  although  revised  in  some 
particulars  after  it  had  been  submitted  by  him.  The  illustrations 
used  are  from  photographs  taken  for  this  work  by  the  junior  author, 
with  the  exception  of  the  text  figures  and  the  illustrations  of  insects 
often  mistaken  for  the  boll  weevil,  of  which  those  marked  "original" 
are,  with  one  exception,  from  drawings  prepared  by  Miss  L.  L.  How- 
enstein,  one  of  the  artists  of  the  Division  of  Entomology. 


CONTENTS. 


I'HL"\ 

Qeneral  considerations     .._..  11 

Historical 11 

1  Vstructiveness - 14 

Territory  affected 10 

Prospects 18 

Life  history 20 

Summary 20 

The  egg 20 

Embryonic  development  .  _ _ .  21 

Length  of  egg  stage 21 

Hatching 22 

Eating  of  eggs  deposited  outside 22 

Percentage  of  eggs  that  hatch 23 

The  larva 23 

Description 23 

Growth 24 

Molts 24 

Process  of  molting ... 24 

Length  of  larval  stage 25 

Pnpal  cells  in  bolls 26 

Pupation 26 

The  pupa 26 

Length  of  pupal  stage 27 

Effect  of  burying  squares  upon  pupation  and  the  escape  of  adults. .  28 

The  adult 29 

Before  emergence 29 

Emergence 29 

Changes  after  emergence 29 

Size  of  weevils . __ .  30 

Relation  of  size  to  food  supply 30 

Weight  of  adults 30 

Color 31 

Size  and  color  not  indicative  of  sex 31 

Proportions  of  the  sexes 32 

Length  of  life  upon  squares .  _ 33 

Length  of  life  on  bolls  alone . 34 

Length  of  life  on  cotton  leaves  alone _  _ .    .    .  34 

Length  of  life  with  sweetened  water  and  with  molasses .  33 

Length  of  life  without  food,  but  with  water 3o 

Length  of  life  without  food  or  water 35 

Cannibalism 36 

5 


Hal  )its  . 

Food  habits 

Larval 

Adult 

Male 

Female 

Males  and  females  together 

Feeding  of  hibernated  weevils  on  early  cotton 

Increase  in  leaf  area  of  cotton . 

Effects  of  feeding  upon  squares  and  bolls 

Destructive  power  by  feeding 

Susceptibility  of  various  cottons ...  1 

Has  the  weevil  any  other  food  plant? 

Insects  often  mistaken  for  the  boll  weevil 

Is  cotton-seed  meal  attractive  ? 

Laboratory  observations 

Field  tests 

The  possibility  of  baiting  weevils  with  sweets 

Attractiveness  of  various  sweets 

Attractiveness  to  hibernated  weevils  in  laboratory  _  _ . 

Influence  of  sweetened  water  upon  feeding  of  weevils  on  cotton 

plants  . . . . . 

Field  tests  for  hibernated  weevils,  using  pure  molasses 

Feigning  death 

Reproduction 

Method  of  making  field  observations  upon  work  of  weevils 

Fertilization 

Age  of  beginning  copulation 

Sexual  attraction  and  duration  of  copulation . 

Duration  of  fertility  in  isolated  females 

Oviposition 

Age  of  beginning  oviposition 

Examination  of  squares  before  oviposition . 

Selection  of  uninf ested  squares  for  oviposition 

Laboratory  observations 

Field  observations 

Activity  of  weevils  in  different  parts  of  the  day 

Place  of  egg  deposition. 

Position  of  weevil  while  puncturing  for  oviposition :  _' 

The  act  of  oviposition 

Time  required  to  deposit  an  egg 

Rate  of  oviposition — average,  maximum 

Stimulating  effect  of  abundance  of  squares  on  egg  deposition 

Relation  of  warts  to  oviposition 

Effects  of  oviposition  upon  squares — flaring,  falling 

Period  of  oviposition 

Does  parthenogenesis  occur  ? 

Development 

Percentage  of  weevils  developed  from  infested  squares 

Development  of  weevils  in  squares  which  never  fall 

Length  of  life  cycle 

Broods  or  generations 


Page. 
36 
37 
37 
37 
39 
39 
40 
40 
41 
43 
44 
44 
47 
48 
50 
50 
51 
52 
52 
53 

54 
55 

:>c> 
56 
56 
57 
57 
57 
58 
58 
58 
59 
59 
60 
61 
63 
65 
65 
66 
67 


69 
70 
72 
72 
73 
73 
73 
74 
75 


I  )r\  el<  ipmenl     ( \  »nt  inued. 

Thermal  influence  upon  activity  and  development 

Laboratory    experiment    in   effect    of    temperatnre   upon    locomotive 

activity 

Hibernation  90 

Length  of  hibernat  ion  period  82 

Apparently  favorable  conditions  for  hibernation  s:'> 
Percentage  of  weevils  hibernating  successfully 

Seasonal  hist*  >ry  8 1 

Emergence  From  hibernat  ion  M 

Apparent  dependence  of  reproduction  upon  food  obtained  from  squares  86 

Progress  of  infestation  in  fields  86 

Weevil  injury  r.  square  production                                    ..  88 

Relation  of  weevils  to  "  top  crop  " - '-'i 

Some  reasons  for  early  destruction  of  stalks      ...  92 

Dissemination .  - 94 

Weevils  in  Beed  houses  at  ginneries         .. 94 

Nat  oral  control . 9."i 

Mechanical  control  . 95 

Pilose  obstacles  to  weevil  progress 95 

Destruction  of  larva  and  pupae  in  bolls  and  squares  by  abnormal 

plant  growth '.•<*» 

Climatic  control _    97 

Influence  of  climatic  conditions  upon   weevil  multiplication  and 

injury 97 

Effect  <  »f  rains  upon  development  of  weevils 98 

Effects  of  wet  winter  weather  on  hibernating  weevils 99 

Effects  of  overflows  in  fields 99 

Laboratory  observations  upon  time  weevils  will  float  and  endure 

submergence 100 

Probabilities  as  to  influence  of  climate  on  weevils  in  cotton  regions 

not  now  infested 101 

Diseases 104 

Parasites .__  lo."» 

Breeding  of  parasites 105 

Pediculoides  ventricosus 1 .  _ 107 

Predatory  enemies . . 109 

Insects 109 

Birds 110 

Methods  of  combating  the  weevil  .. 110 

( "ultural  methods ...  Ill 

Futile  means                                                ....    112 

Bibliography .  _ 113 


ILLUSTRATION'S. 


PLATES. 


Plate  I.  Fig.     1.— Cotton  boll  weevil Frontispiece 

Fig.    2. — Weevil  feigning  death Frontispiece 

Fig.    3. — Two  eggs  and  feeding  excavation  in  a  square  - . .  Frontispiece 

Fig.    4. — Full-grown  larva Frontispiece 

Fig.    5. — Pupa,  ventral  view Frontispiece 

Fig.    G. — Pupa,  side  view Frontispiece 

Fig.    7. — Larva,  full-grown Frontispiece 

Fig.    8. — Pupa Frontispiece 

Fig.    9.— Adult Frontispiece 

Fig.  10. — Weevils  feeding  on  boll Frontispiece 

Fig.  11 . — Larva  developing  in  boll Frontispiece 

II.  Fig.  12. — Collection  showing  life  history  and  work  of  boll  weeviL  _        24 

III.  Fig.  13. — Two  weevils  feeding  on  a  square 24 

Fig.  14.— Egg  isolated 24 

Fig.  15. — Full-grown  larva  in  square 24 

Fig.  16.— Full-grown  larva  isolated 24 

Fig.  IT.— Pupa 24 

Fig.  18. — Adult  just  transformed 24 

Fig.  19. — Large  larvae  in  large  boll  __- 24 

Fig.  20. — Pupal  cell  in  boll  broken  open 24 

IV.  Fig.  21. — Emergence  hole  made  by  weevil  in  square 32 

Fig.  22. — Weevil  escaping  normally  from  boll 32 

Fig.  23. — Apparatus  used  in  breeding  weevils 32 

Fig.  24. — Larva  destroying  the  ovary  and  preventing  bloom  in  32 

large  square 32 

Fig.  25. — Leaf  fed  upon  by  weevils  in  confinement 32 

Fig.  26. — Emergence  hole  of  weevil  from  boll  which  never  opened.        32 

V.  Fig.  27. — Larva  in  square,  ovary  untouched 32 

Fig.  28. — Large  and  small  larva?  in  boll 32 

VI.  Fig.  29.— Square  much  fed  upon 48 

Fig.  30. — Distorted  bloom,  caused  by  feeding  upon  large  square.  _        48 

VII.  Fig.  31. — Blooms  distorted  by  feeding  punctures,  open  but  imper-  48 

feet . 48 

Fig.  32. — Small  boll  riddled  by  feeding  punctures 48 

Fig.  33. — One  lock  of  boll  destroyed  by  feeding  punctures 48 

VIII.  Fig.  34.— External  appearance  of  large  boll  much  fed  upon 56 

Fig.  35. — Internal  appearance  of  same  boll ... 56 

IX.  Fig.  36. — Cages  used  to  confine  weevils  in  field 56 

Fig.  37. — Plant  showing  tagged  squares  from  cage  work 56 


9 

IMvii     x.  Pig   88,     Boll  showing  two  la  troyed   bj   two  feed 

punctures  made  bj  a  male  wreevil 
i     .  89,    Square  showing  externa]  appearanc  lof  t  w  egg  pnnc 

hires  :,,; 
Fig,  it  i.     Waii  formed  on  side  of  Bqnare  In  healing  an  egg  pnnc 

hire  :,,; 

Fig.  ii.     Egg  deposited  on  inside  of  carpel  of  a  boll  66 

Fig.  Id.     Normal  and  flared  squares  56 

XI.  Fig,  18.    Three  large  larvae  in  a  boll  64 
Fig.  1 1.  —  Four  papal  cells  from  bolls  on  left  compared  with  four 

c>t ton  seeds  on  right  64 

XII.  Fig.  45.     Device  used  to  test  attraction  of  molasses  in  the  field 

in  spring  . -  -  -  64 

Fig.  !»'».    -Fallen  squares  on  gronnd  in  field <*>l 

Fig.  -IT. — Squares  dried  and  still  hanging  upon  the  plant  <i  I 
Fig.  48. — Device  used  to  test  relative  attractiveness  t<>  weevils 

of  American  and  Egyptian  squares 64 

XI II.  Fig.  4'.).— Device  used  to  test  effect  of  temperature  upon  weevil 

activity 80 

Fig.  50. —  Comparison  of  pilosity  on  "  King  "  (at  left  I  and  li  Mit 

Ann-'  (at  right)  stems 80 

Fig.  51. — Locality  found  very  favorable  to  hibernation  of  many 

weevils s(> 

XIV.  Figs.  50   and   5:5. — Mexican   cotton   boll   weevil    {Anthonomus 

gran  (lis) 80 

Fig.  54.  —  Lixus  sp__. 80 

Fig.  55. — Acorn  weevil  {Balaninus  uniformis  auct.)  a.  female, 
dorsal  view:   b,  same,  lateral  view:  c,  head,  snout, 

and  antenna  of  male 80 

Fig.  56. — Apple  curculio  (Coccoto)-us  scutellaris) Si) 

Fig.  57. — Plum  gouger  {Anthonomus prunicida) 80 

Fig.  58. — Des)noris  scajxilis _•. 80 

XV.  Figs.  59  and  60. — Transverse  Baris  (Baris  transversa) 90 

Fig.  61. — Centrinus  penicellus 96 

Fig.  62. — Coffee  bean  weevil  (Arcecerus  faseiculatus):  a.  larva: 

o,  beetle;  c.  pupa 96 

Figs.  63  and  64. — ChalcocU  rmus  ceneus 96 

XVI.  Figs.  65  and  66. — Sharpshooter  (Homalorfisca  triquetra) 96 

Fig.  67. — Cotton  stainer  {Dysdercus  suturellus) 96 

Fig.  68. — Cotton  stalk  borer  {Ataxia  erypta).^. 96 

Fig.  69. — Imbricated  snout-beetle  {Epiccerus  imbricatus)  96 

Fig.  70. — A  snapping  beetle  (Monocrcpidins  vespertinus) 96 

TEXT  FIGURES. 

Fig.  1.  Map  of  area  infested  by  weevil .. 17 

2.  Mexican  boll  weevil,  head  showing  rostrum  and  antenna'  38 

3.  Diagram  showing  activity  of  5  female  weevils .  64 

4.  Bracon  mellitor 106 

5.  Enemy  of  boll  weevil .  Pedieuloides  ventricosus   107 

6.  Solenopsis  debilis  var.  texana 109 


THE  MEXICAN  COTTON  BOLL  WEEVIL 


GENERAL  CONSIDERATIONS. 
HISTORICAL. 

There  is  very  Little  certainty  regarding  the  history  of  the  Mexican 

cotton  boll  weevil  before  it  came  to  the  attention  of  the  Division  of 
Entomology  in  Texas  in  L894.     The  species  was  described  by  Boheman 

in  IS4:>  from  specimens  received  from  Vera  Cruz,  and  it  was  recorded 
by  SnlVrian  in  1871  as  occurring  at  Cardenas  and  San  Cristobal  in 
Cuba.  Written  documents  in  the  archives  at  Monclova,  in  the  State 
of  Coahuila,  Mexico,  indicate  that  the  cultivation  of  cotton  was  prac- 
tically abandoned  in  the  vicinity  of  that  town  about  the  year  L848,  or 
at  least  that  some  insect  caused  very  great  fears  that  it  would  be  nec- 
essary to  abandon  the  cultivation  of  cotton.  A  rather  careful  inves- 
tigation of  the  records  makes  it  by  no  means  clear  that  the  insect  was 
the  boll  weevil,  although  there  is  a  rather  firmly  embedded  popular 
notion  in  Mexico,  as  well  as  in  the  Southern  United  States,  that  the 
damage  must  have  been  perpetrated  bj^  that  species.  As  far  as  the 
accounts  indicate,  it  might  have  been  the  boll  worm  (HeLiothis  armi- 
ger)  or  the  cotton  caterpillar  (Ah  fia  argillacea). 

From  the  time  of  the  note  by  Suffrian  regarding  the  occurrence  of 
the  weevil  in  Cuba  in  1871  up  to  1885  there  has  been  found  no  pub- 
lished record  concerning  it.  In  1885,  however,  C.  V.  Riley,  then 
Entomologist  of  the  Department  of  Agriculture,  published  in  the 
report  of  the  Commissioner  a  very  brief  note  to  the  effect  that  Antho- 
nomas  grand  is  had  been  reared  in  the  Department  from  dwarfed  cot- 
ton bolls  sent  by  Dr.  Edward  Palmer  from  northern  Mexico.  This  is 
the  first  account  associating  the  species  with  damage  to  cotton.  The 
material  referred  to  was  collected  in  the  State  of  Coahuila,  supposedly 
not  far  from  the  town  of  Monclova.  The  exact  date  at  which  the 
insect  crossed  the  Rio  Grande  into  Texas  is  as  uncertain  as  the  means 
whereby  this  was  accomplished.  All  that  can  be  found,  which  is 
mostly  in  the  form  of  testimony  of  planters  in  the  vicinity  of  Browns- 
ville, indicates  that  the  pest  first  made  its  appearance  in  that  locality 
about  1802.  In  1801  it  had  spread  to  half  a  dozen  counties  in  the 
Brownsville  region,  and  during  the  last  months  of  the  year  was 
brought  to  the  attention  of  the  Division  of  Entomology  as  an  impor- 
tant enemy  of  cotton.     Mr.  C.  II.  T.  Townsend  was  immediately  sent 

11 


12 

to  the  territory  affected.  His  report  was  published  in  March,  1895. 
It  dealt  with  the  life  history  and  habits  of  the  insect,  which  were 
then  completely  unknown,  the  probable  method  of  its  importation, 
the  damage  that  might  result  from  its  work,  and  closed  with  recom- 
mendations for  fighting  it  and  preventing  its  further  advance  in  the 
cotton-producing  regions  of  Texas.  It  is  much  to  be  regretted  that 
the  State  of  Texas  did  not  adopt  at  that  time  the  suggestion  made  by 
the  Division  of  Entomology  that  a  belt  be  established  along  the  Rio 
Grande  in  which  the  cultivation  of  cotton  should  be  prohibited,  and 
thus  cut  off  the  advance  of  the  insect. 

The  events  of  the  last  few  years  have  verified  the  prediction  of  the 
Division  of  Entomology  in  regard  to  the  advance  made  and  the  dam- 
age caused  by  the  insect. 

In  1895  the  insect  was  found  by  the  entomologists,  who  continued 
the  investigation  started  the  year  before,  as  far  north  as  San  Antonio 
and  as  far  east  as  Wharton.  Such  a  serious  advance  toward  the 
principal  cotton-producing  region  of  the  State  caused  the  Division  to 
continue  its  investigations  during  practically  the  whole  season.  The 
results  of  this  work  were  incorporated  in  a  circular  by  Doctor  Howard, 
published  early  in  1896,  in  both  Spanish  and  English  editions. 

An  unusual  drought  in  the  summer  of  1896  prevented  the  maturity 
of  the  fall  broods  of  the  weevil,  and  consequently  there  was  no  exten- 
sion of  the  territory  affected.  It  should  be  stated  in  this  connection 
that  the  region  from  San  Antonio  to  Corpus  Christi  and  thence  to 
Brownsville  will  frequently  pass  through  similar  experiences,  which 
will  be  quite  different  from  anything  that  may  be  expected  to  occur 
in  regions  where  the  rainfall  is  more  certain.  In  1900  as  well  as  in 
1903,  in  all  or  part  of  the  region  referred  to,  the  numbers  of  the  weevil 
were  reduced  by  climatic  conditions,  principally  a  scanty  rainfall,  so 
that  they  were  comparatively  unimportant  factors.  During  1896  the 
investigations  were  continued  and  the  results  published  in  another 
circular  issued  in  February,  1897.  This  circular  was  published  in 
Spanish  and  German,  as  well  as  English  editions,  for  the  benefit  of  the 
very  large  foreign  population  in  southern  Texas. 

The  season  of  1897  was  in  many  respects  almost  as  unfavorable  as 
that  of  1896,  although  the  pest  increased  its  range  to  the  region  about 
Yoakum  and  Gonzales.  Although  this  extension  was  small  it  was 
exceedingly  important,  because  the  richest  cotton  lands  in  the  United 
States  were  beginning  to  be  invaded.  The  problem  had  thus  become 
so  important  that  Mr.  Townsend  was  stationed  in  Mexico,  in  a  region 
supposed  to  be  the  original  home  of  the  insect,  for  several  months  to 
discover,  if  possible,  any  parasites  or  diseases  that  might  be  affecting 
it,  with  the  object  of  introducing  them  to  prey  upon  the  pest  in  Texas. 
Unfortunately  nothing  was  found  that  gave  any  hope  of  material 
assistance  in  the  warfare  against  the  weevil. 

The  season  of  1898  was  very  favorable  for  the  insect.     Bastrop, 


18 

L©e,  and  Burleson  counties  became  invaded,  and  some  Isolated  oolo 
oies  were  found  across  the  Brazos  River,  in  Waller  and  Brazos  coun 
lies,  investigations  by  the  Division  of  Entomology  were  continued, 
and  a  summary  of  the  work,  dealing  especially  with  experiments 
conducted  by  Mr.  C.  L.  Marlatt  in  the  spring  of  L896,  was  published 
in  still  another  circular.  At  this  time  the  legislature  of  the  State  of 
Texas  made  provision  for  the  appointment  of  a  State  entomologist 
and  provided  a  Limited  appropriation  for  an  investigation  of  means 
of  combating  the  boll  weevil.  In  view  of  this  lad  the  Division  of 
Entomology  disconl  inued,  temporarily,  the  work  t  hat  had  been  carried 
on  by  having  agents  in  the  field  almost  constantly  for  four  years,  and 
all  correspondence  was  referred  to  the  State  entomologist;  but, 
unfortunately,  the  insect  continued  to  spread,  and  it  soon  became 
apparent  that  other  States  than  Texas  were  threatened.  This  caused 
the  work  to  be  taken  up  anew  by  the  Division  of  Entomology  in 
1901,  in  accordance  with  a  special  appropriation  by  Congress  for  an 
investigation  independent  of  that  being  carried  on  by  the  State  of 
Texas  and  with  special  reference  to  the  discovery,  if  possible,  of 
means  of  preventing  the  insect  from  spreading  into  adjoining  Stales. 
In  accordance  with  this  provision  an  agent  was  sent  to  Texas  in 
March  and  remained  in  that  State  until  December.  lie  carried  on 
cooperative  work  upon  eight  of  the  larger  plantations  in  the  weevil 
region.  The  result  of  his  observations  was  to  suggest  the  advisability 
of  a  considerable  enlargement  of  the  scope  of  the  work.  It  had  been 
found  that  simple  cooperative  work  with  the  planters  was  exceedingly 
unsatisfactory.  The  need  of  a  means  of  testing  the  recommendations 
of  the  Division  of  Entomology  upon  a  large  scale,  and  thereby  furnish- 
ing actual  demonstrations  to  the  planters,  became  apparent.  Conse- 
quently, at  the  suggestion  of  the  Department  of  Agriculture,  provision 
for  an  enlargement  of  the  work  was  made  by  Congress.  Agreements 
were  entered  into  with  two  large  planters  in  typical  situations  for  t  est  - 
ing  the  principal  features  of  the  cultural  system  of  controlling  the 
pest  upon  a  large  scale.  In  this  way  125  acres  at  Victoria  and  200 
acres  at  Calvert  were  employed.  At  the  same  time  the  headquarters 
and  laboratory  of  the  special  investigation  were  established  at  Vic- 
toria, and  such  matters  as  parasites,  the  possibility  of  poisoning  the 
pest  or  of  destroying  it  by  the  use  of  machines,  as  well  as  investigat- 
ing man}-  of  the  features  of  its  biology  that  were  still  absolutely 
unknown,  were  given  careful  attention  by  a  specially  trained  assistant 
whose  services  were  procured  for  that  purpose.  The  results  of  the 
field  work  for  this  }ear  were  published  in  the  form  of  a  Farmers' 
Bulletin  entitled  ''Methods  of  Controlling  the  Boll  Weevil;  Advice 
Based  on  the  AVork  of  1902;"  but  on  account  of  the  late  date  of  the 
establishment  of  the  laboratory  (June),  and  the  consequent  incom- 
pleteness of  many  of  the  records,  it  was  not  thought  advisable  to 
publish  anything  concerning  the  laboratory  investigations.     During 


14 

this  season  cooperation  was  carried  on  with  the  Mexican  commission 
charged  with  the  investigation  of  the  boll  weevil  in  that  country,  which 
was  arranged  on  the  occasion  of  a  personal  visit  of  Dr.  L.  O.  Howard 
to  the  City  of  .Mexico  in  the  fall  of  11)01.  Specimens  of  parasites  were 
frequently  exchanged,  and  through  the  courtesy  of  Prof.  A.  L. 
Herrera,  chief  of  the  Mexican  commission,  an  agent  in  charge  of  the 
investigation  in  Texas  visited  the  laboratories  at  the  City  of  Mexico 
and  Cuernevaca,  where  a  study  was  made  of  the  methods  of  propa- 
gating parasites,  especially  Pediculoides  ventricosus  Newp.  A  large 
number  of  specimens  of  this  mite  was  brought  back  to  Texas,  where 
they  were  carried  through  the  winter  successfully  and  used  in  field 
experiments  the  following  season. 

The  favorable  reception  by  the  planters  of  Texas  of  the  experi- 
mental field  work  conducted  during  this  season,  with  the  increased 
territory  invaded  by  the  pest,  brought  about  an  enlarged  appropria- 
tion for  the  work  of  1903.  By  enactment  which  became  effective  on 
the  1th  of  March  830,000  was  placed  at  the  disposal  of  the  Division  of 
Entomology.  It  thus  became  possible  to  increase  the  number  and  size 
of  our  experimental  fields  as  well  as  to  devote  more  attention  to  the 
investigation  of  matters  suggested  by  previous  work  in  the  laboratory . 
Seven  experimental  farms,  aggregating  558  acres,  were  accordingly 
established  in  as  many  distinct  cotton  districts  in  Texas.  Despite 
generally  very  unfavorable  conditions  the  results  of  this  experi- 
mental work  demonstrated  many  important  points.  The  principal 
ones  are  detailed  in  Farmers'  Bulletin  No.  189  of  this  Department. 

DESTRUCTIVENESS. 

Various  estimates  of  the  loss  occasioned  to  cotton  planters  by  the 
boll  weevil  have  been  made.  In  the  nature  of  the  case  such  estimates 
must  be  made  upon  data  that  is  difficult  to  obtain  and  in  the  collec- 
tion of  which  errors  must  inevitably  occur.  There  is,  of  course,  a 
general  tendency  to  exaggerate  agricultural  losses,  as  well  as  to  attrib- 
ute to  a  single  factor  damage  that  is  the  result  of  a  combination  of 
many  influences.  Before  the  advent  of  the  boll  weevil  into  Texas 
unfavorable  weather  at  planting  time,  summer  droughts,  and  heavy 
fall  rains  caused  very  light  crops  to  be  produced.  Now,  however,  the 
tendency  is  everywhere  to  attribute  all  of  the  shortage  to  the  weevil. 
Nevertheless,  the  pest  is  undoubtedly  the  most  serious  menace  that 
the  cotton  planters  of  the  South  have  ever  been  compelled  to  face,  if 
not,  indeed,  the  most  serious  danger  that  ever  threatened  any  agri- 
cultural industry.  It  was  generally  considered,  until  the  appearance 
of  the  pest  in  Texas,  that  there  were  no  apparent  difficulties  to  prevent 
an  increase  in  cotton  production  that  would  keep  up  to  the  enlarging 
demand  of  the  world  until  at  least  twice  the  present  normal  crop  of 
about  10,500,000  bales  should  be  produced.  Now,  however,  in  the 
opinion  of  most  authorities,  the  weevil  has  made  this  possibility  very 


L5 

doubtful,  although  the  Aral  fears  entertained  in  man}  localities  that 
the  cultivation  of  cotton  would  have  to  be  abandoned  have  generally 
been  given  up.  An  especially  unfavorable  feature  of  the  problem  is 
in  the  fact  thai  the  weevil  reached  Texas  at  whai  would  have  been, 
from  other  considerations,  the  most  critical  time  in  the  history  of  the 
production  of  the  Btaple  in  the  State.  The  natural  fertility  of  the 
cotton  lauds  had  been  bo  great  that  planters  had  neglected  complete^ 
such  matters  as  seed  selection,  varieties,  ferf  ilizers,  and  rot  a i  ion,  that 
in  usi  eventually  receive  consideration  in  any  cotton-producing  coun- 
try. In  general,  the  only  seed  used  was  from  the  crop  of  the  preced- 
ing year,  unselected  and  of  absolutely  unknown  variety,  and  the  use 
of  fertilizers  had  not  been  practiced  al  all.  Although  ii  is  by  no 
im  'a  ns  i  rue  ih.ii  the  fertility  of  the  soil  had  been  exhausted,  neverthe- 
less, <>ii  many  of  the  older  plantations  in  Texas  the  continuous  plant- 
ing of  cotton  with  a  run-down  condition  of  the  seed  combined  to  make 
a  change  necessary  in  order  to  continue  the  industry  profitably. 

A  careful  examinal  ion  of  the  stal  ist  ics,  to  which  more  complete  ref- 
erence is  made  in  Farmers'  Bulletin  No.  189,  has  indicated  thai  the 
pes!  causes  a  reduetion  in  production  for  a  few  years  after  its  ad  venl 
{>['  about  50  per  cent,  hut  at  the  same  time  it  is  evident  that  most 
planters  within  a  few  years  are  able  to  adopt  the  changes  in  the  sys- 
tem of  cultivating  this  staple  that  are  made  necessary  by  the  weevil, 
so  that  the  damage  after  a  short  time  does  not  compare  with  that  at 
the  beginning.  Upon  the  foregoing  basis,  during  the  season  of  1903 
the  weevil  caused  Texas  cotton  planters  a  loss  of  about  $15,000,000, 
and  tins  estimate  agrees  rather  well  with  estimates  made  in  other 
ways  by  the  more  conservative  cotton  statisticians.  A  similar  esti- 
mate made  in  1902  led  to  the  conclusion  that  the  damage  amounted 
to  about  $K  »,000,i »<>< i.  It  consequently  appears  that  during  the  years 
the  pest  has  been  in  Texas  the  aggregate  damage  would  reach  at  least 
$50,000,000.  .Many  conditions  of  climate  and  plantation  practice  in 
the  eastern  portion  of  the  cotton  belt  indicate  that  the  weevil  prob- 
lem will  eventually  be  as  serious  east  of  the  Mississippi  as  it  now  is 
in  Texas.  According  to  the  estimates  of  Mr.  Richard  II.  Edmunds, 
the  editor  of  Manufacturers'  Record,  the  normal  cotton  crop  of  the 
United  states  represents  a  value  of  $500,000,000,  the  extreme  ulti- 
mate damage  that  the  pest  might  accomplish  over  the  entire  belt 
would  be  in  the  neighborhood  of  $250,000,000 annually, provided  none 
of  the  means  of  avoiding  damage  that  are  now  coming  into  common 
use  in  Texas  were  adopted.  In  spite  of  the  general  serious  outlook, 
however,  it  must  be  stated  that  fears  of  the  damage  the  weevil  may 
do  are  very  often  much  exaggerated,  especially  in  newly  invaded 
regions.  It  is  not  at  all  necessary  to  abandon  cotton.  The  work  of  the 
Division  of  Entomology  for  several  seasons  has  demonstrated  that  a 
crop  can  be  grown  profitably  in  spite  of  the  boll  weevil,  and  this  expe- 
rience is  duplicated  by  many  planters  in  Texas. 


16 

TERRITORY  AFFECTED. 

At  the  present   time  the  boll  weevil  lias   no!   been  found  in  the 

Tinted  States  outside  of  Texas  (see  fig.  1)  except  in  three  instances 
in  Louisiana.  In  one  of  these  cases,  at  the  sugar  experiment  station 
a1  Audubon  Park,  in  the  vicinity  of  New  Orleans,  the  circumstances 
have  led  the  State  authorities  to  the  conclusion  that  the  pests 
purposely  placed  in  the  fields.  The  other  two  eases  are  isolated  oc- 
currences in  Sabine  Parish,  in  the  extreme  western  part  of  the  State. 
Both  of  these  are  apparently  traceable  to  importation  from  the  oppo- 
site county  in  Texas,  in  cotton  seed  used  for  planting  purposes  or 
possibly  in  hay.  The  authorities  totally  destroyed  the  cotton  grow- 
ing at  the  experiment  station  at  Audubon  Park,  La.,  as  soon  as  the 
presence  of  the  weevils  was  discovered.  As  no  cotton  is  grown 
within  9  miles  of  that  point,  it  seems  altogether  likely  thai  the  colony 
may  have  been  completely  exterminated.  Similar  action  is  bein. 
taken  regarding  the  two  colonies  found  in  Sabine  Parish. 

In  Texas  the  infested  area  extends  from  Brownsville,  where  tin- 
weevil  originally  entered  the  State,  to  Sherman.  Shelby  and  Morris 
counties  represent  the  extreme  eastern  range.  The  cotton  acreage 
involved  in  this  territory  includes  about  30  per  cent  of  the  cotton 
acreage  of  the  United  States,  which  produced  in  1900  about  35  per 
cent  of  the  total  crop  of  this  country,  or  about  one-fourth  of  the  crop 
of  the  world  for  that  jTear.  There  is,  however,  a  considerable  bell 
between  about  the  latitude  of  Dallas  and  the  Red  River  where  th« 
pest  does  not  occur  in  uniform  numbers  in  all  cotton  fields,  and  con- 
sequentl}7  the  general  damage  has  not  been  great.  It  may  be  a  mat  1  er 
of  only  two  or  three  years  before  it  will  become  sufficiently  numerous 
to  cut  down  the  total  production. 

There  are  some  features  of  special  interest  in  the  situation  in  Cuba. 
Although  the  weevil  has  long  been  known  to  occur  in  the  island,  it 
has  attracted  very  little  attention  on  account  of  the  fact  that  the  cul- 
tivation of  cotton  was  abandoned  for  a  long  time  in  favor  of  crops  that 
have  been  more  profitable.  Now,  however,  with  the  better  price  of  the 
staple  and  rather  unsatisfactory  returns  from  some  other  crops,  cot- 
ton is  being  planted  upon  a  considerable  scale.  Mr.  E.  A.  Schwa rz 
was  sent  to  the  island  on  two  occasions  to  study  the  conditions  there. 
Although  his  report  refers  especially  to  the  Province  of  Santa  Clara, 
it  is  probably  true  that  conditions  similar  to  those  he  describes  obtain 
everywhere.  He  found  that  the  entire  province  is  naturally  more  oi- 
lers infested  by  the  boll  weevil,  and  that  weevils  did  not  spread  from 
cultivated  cotton  planted  with  seed  obtained  in  the  United  States  to 
the  wild  plants,  as  at  first  supposed,  but  from  the  latter  to  the  former. 
The  weevils  were  found  to  be  more  numerous  on  the  kidne}7  cotton 
growing  wild  than  on  the  loose  cotton  (seminiella).  The  latter,  when 
growing  alone,  was  usually  found  to  be  free  from  weevils,  but  liable 
to  be  infested  when  growing  in  the  vicinity  of  kidney  cotton.     A  large 


IT 


MEXICO 


Fig.  1.— Map  showing  area  infested  by  Mexican  cotton  bull  weevil  (redrawn.  > 
21739— No.  45—04 2 


18 

number  of  wild  cotton  trees  growing  in  the  vicinity  of  dwellings  or 
growing  entirely  wild  are  always  infested,  and  here  the  weevils  are 
more  numerous,  bu1  never  as  numerous  as  on  the  cultivated  Egyptian 
cotton.  Al  one  locality,  where  a  large  number  of  kidney  cotton  trees 
were  glowing  (about  50  plants,  some  of  them  probably  20  years  old), 
il  was  found  that  at  least  one  out  of  every  twenty  squares  had  been 
punctured  by  the  first  week  in  March.  From  Mr.  Schwarz's  report 
it  does  not  seem  that  there  is  a  very  promising  outlook  for  cotton 
raising  in  Cuba.  The  presence  of  wild  perennial  cotton,  upon  which 
the  weevil  probably  exists  everywhere,  will  always  be  a  source  of 
danger.  The  long  moist  seasons  and  mild  winters  will  form  more 
favorable  conditions  for  the  pest  than  will  occur  anywhere  in  the 
United  States. 

PROSPECTS. 

The  investigations  of  the  life  history  of  the  weevil  that  are  referred 
to  in  detail  in  the  following  pages  have  indicated  that  the  most  im- 
portant elements  in  limiting  the  spread  of  an  insect — namely,  win- 
ter temperatures  and  parasites — in  this  case  offer  no  assurance  that 
the  pest  will  soon  be  checked.  For  the  past  ten  years,  except  where 
local  unfavorable  conditions  have  interfered,  it  has  advanced  annu- 
ally a  distance  of  about  50  miles.  The  insect  is  undoubtedly  chang- 
ing its  habits  and  adapting  itself  to  climatic  conditions  in  newT  regions 
that  it  is  invading.  It  is  undoubtedly  true  that  it  has  acquired  an 
ability  to  withstand  more  severe  frosts  than  occurred  in  the  vicinity 
of  San  Antonio  in  1895.  Except  in  a  few  particular  regions,  however, 
it  does  not  seem  that  the  continued  spread  will  be  as  rapid  as  it  has 
been.  The  country  between  Gonzales  Count}*  and  the  Red  River  is 
practically  a  continuous  cotton  field,  and  the  prevailing  winds  have 
undoubtedly  favored  the  northward  spread  of  the  insect.  Similar 
conditions  will  now  favor  a  rapid  extension  into  the  Red  River  valley 
in  Louisiana,  and  likewise  there  seems  no  doubt  that  the  spread' will 
be  rapid  in  the  Yazoo  valley  in  Mississippi;  but  in  most  other  situa- 
tions throughout  the  belt  the  cotton  fields  are  smaller  and  more  iso- 
lated than  is  the  case  in  Texas;  consequently  it  is  to  be  supposed 
that  the  spread  of  the  pest  will  be  retarded  somewhat. 

Basing  estimates  on  a  careful  study  of  the  distance  the  boll  weevil 
has  traveled  each  year,  as  well  as  upon  some  attention  that  has  been 
paid  to  the  means  wiiereb}*  it  reaches  new  territory,  referred  to  more 
in  detail  hereafter  (p.  9-4),  it  seems  safe  to  predict  that  in  from  fifteen 
to  eighteen  years  the  pest  will  be  found  throughout  the  cotton  belt. 
During  the  time  it  has  been  in  Texas  there  has  been  no  tendency 
toward  dying  out,  and  in  south  Texas  the  pest  is  practically  as  trou- 
blesome, except  in  so  far  as  it  is  affected  by  changes  in  managing  the 
crop,  as  it  was  in  1895.  In  Mexico,  where  it  has  existed  for  a  much 
longer  period,  it  is  apparently  as  plentiful  as  ever.  Careful  attention 
that  has  been  paid  to  the  study  of  parasites  and  diseases,  as  well  as 


L9 

temperatures  unfavorable  to  the  insect,  lias  failed  to  reveal  anj  pros 
peel  that  ii  nn  i 1 1  ever  1  *« *  muoli  less  troublesome  than  now.  There 
will,  nevertheless,  be  seasons  from  time  t<>  time  in  \\  1 1 i «•  1 1  the  damage 
will  be  much  less  than  normal.  Climatic  conditions  will  undoubtedly 
cause  temporary  diminution  of  1 1 1« *  numbers  of  the  pest  in  certain 
localities.  In  Texas  these  conditions  have  given  rise  almost  every 
year  to  the  supposition  on  the  part  of  the  planters  that  the  insects 
have  died  out.  This  was  especially  the  case  in  the  region  between 
San  Antonio  and  Beeville  in  L900,  and  in  the  vicinity  of  Corpus 
Christi  in  L903.  Both  these  years  followed  a  series  of  seasons  in 
which  there  was  much  Less  than  the  normal  rainfall;  consequently  not 
only  had  a  great  many  of  the  weevils  been  killed,  but  the  numbers 
had  been  diminished  by  reason  of  the  very  Limited  extent  to  which  LI 
was  possible  to  raise  cotton.  Both  L900  and  L903,  however,  were 
exceedingly  favorable  for  cotton.  Early  planting  was  possible,  and 
there  was  an  abundance  of  rain  throughout  the  season.  The  crop 
was  so  far  advanced  by  the  time  the  weevils  became  numerous  thai  a 
very  fair  yield  was  made,  although  in  neither  of  the  cases  was  any 
top  crop  whatever  produced.  Whenever  a  series  of  years  of  scanty 
rainfall  is  followed  by  one  of  normal  precipitation  the  weevil  will 
temporarily  be  comparatively  unimportant.  The  most  disastrous 
seasons  will  be  those  in  which  the  rainfall  is  excessive  and  planting 
unavoidably  thrown  late. 

In  this  connection  it  becomes  of  some  interest  to  speculate  as  to  the 
possibility  that  the  weevil  may  eventually  be  carried  outside  of  the 
United  States  and  gain  a  foothold  in  other  cotton-prodncing  countries. 
The  fact  that  the  insect  is  rather  rapidly  adapting  itself  to  conditions 
in  the  United  States  that  are  quite  diverse  from  those  of  its  native  home 
leads  to  the  supposition  that  it  would  experience  but  little  difficulty  in 
adapting  itself  to  climatic  conditions  wherever  cotton  may  be  grown. 
This  probability  of  the  spread  of  the  wTeevil  outside  of  the  United 
States  is  increased  by  the  fact  that  cotton  seed  for  planting  purposes 
is  frequently  shipped  from  the  United  States  to  various  parts  of  the 
globe,  and  that  within  the  last  fewr  years  various  conditions  have 
caused  especial  interest  to  be  displayed  in  this  matter.  There  is 
nothing  whatever  to  prevent  weevils  that  may  happen  to  be  sacked 
with  cotton  seed  from  being  carried  long  distances  on  shipboard.  In 
the  semidormant  condition  in  which  they  hibernate  they  have  often 
been  known  to  go  longer  without  food  than  is  ordinarily  required  for 
a  freight  shipment  from  Galveston  to  Cape  Town.  Although  there 
are  no  truly  cosmopolitan  cotton  insects,  it  seems  likely  that  the  boll 
weevil  ma}*  eventually  be  more  widely  distributed  than  any  other. 


20 

LIFE  HISTORY. 

SUMMARY. 

The  egg  is  deposited  by  the  female  weevil  in  a  cavity  formed  by  eat- 
ing into  a  square  or  boll.  The  egg  hatches  in  a  few  days  and  the 
footless  grub  begins  to  feed,  making  a  larger  place  for  itself  as  it 
grows.  During  the  course  of  its  growth  the  larva  sheds  its  skin  at 
least  three  times,  the  third  molt  being  at  the  formation  of  the  pupa, 
which  after  a  few  days  sheds  its  skin,  whereupon  the  transformation 
becomes  completed.  These  immature  stages  require  on  the  average 
between  two  and  three  weeks.  A  further  period  of  feeding  equal  to 
about  one-third  of  the  preceding  developmental  period  is  required  to 
perfect  sexual  maturity  so  that  reproduction  may  begin. 

Variation  in  size  depends  directly  upon  abundance  and  condition 
of  the  food  supply.  Weevils  of  average  size  are  about  8  mm.  in  length, 
one-third  as  broad  as  long,  and  weigh  about  one-fourth  of  a  grain. 
Color  varies  as  widely  as  does  size.  It  is  usually  of  a  gray  or  yellow- 
brown,  and  is  most  markedly  yellow  in  the  largest  weevils.  Sexes 
are  produced  in  practically  equal  numbers,  the  males  predominating 
slightly.  No  other  food  has  been  found  which  will  attract  weevils 
from  squares  and  no  plant  but  cotton  upon  which  they  can  sustain 
themselves  for  any  considerable  length  of  time.     See  PI.  II,  fig.  12. 

THE  EGG. 

The  egg  of  the  boll  weevil  is  an  unfamiliar  object  even  to  many 
who  are  thoroughly  familiar  with  the  succeeding  stages  of  the  insect. 
If  laid  upon  the  exterior  of  either  square  or  boll  it  would  be  fairly 
conspicuous  on  account  of  its  pearly  white  color.  Measurements 
show  that  it  is  on  the  average  about  0.8  mm.  long  by  0.5  mm.  wide. 
Its  form  is  regularly  elliptical  (PI.  Ill,  fig.  14),  but  both  form  and 
size  vary  somewhat.  Some  eggs  are  considerably  longer  and  more 
slender  than  the  average,  while  others  are  ovoid  in  shape.  The  shape 
may  be  influenced  by  varying  conditions  of  pressure  in  deposition 
and  the  shape  of  the  cavity  in  which  it  is  placed.  The  soft  and  deli- 
cate membrane  forming  the  outer  covering  of  the  egg  shows  no  notice- 
able markings,  but  is  quite  tough  and  allows  a  considerable  change 
in  form.  Were  the  eggs  deposited  externally  they  would  doubtless 
prove  attractive  to  some  egg  parasite  as  well  as  to  many  predatory 
insect  enemies.  Furthermore,  the  density  of  the  membranes  would 
be  insufficient  to  protect  the  egg  from  rapid  drying  or  the  effects  of 
sudden  changes  in  temperature.  All  these  dangers  the  weevil  avoids 
by  placing  the  eggs  deeply  within  the  tissue  of  the  squares  or  bolls 
upon  which  she  feeds.  As  a  rule,  the  cavities  which  receive  eggs 
are  especially  prepared  therefor  and  not  primarily  for  obtaining  food. 
Buried  among  the  immature  anthers  of  a  square  or  on  the  inner  side  of 
one  carpel  of  a  boll,  as  they  usually  are,  weevil  eggs  become  very  incon- 
spicuous objects  (PL  I,  fig.  3)  and  are  found  only  after  careful  search. 


21 


EMBRYONIC    m:\  i:i.<  >r\ii 

Owing  to  the  transparency  of  tli<-  egg  membranes,  something  of 
the  development  of  il>"  embryo  can  !><•  Been  through  them,  but  n<> 
special  stud}  has  yel  been  made  upon  the  subject  of  the  embryology 
of  the  weevil.  The  fully  developed  embryo  completely  nils  the  inte- 
rior of  the  egg,  its  large  head  being  in  one  end  and  its  body  curved 
vent  rally  upon  itself  till  nearly  double.  Considerable  mot  ion  is  mani- 
fested if  the  egg  be  touched  at  this  period. 


LENGTH    <>F    EGG    STAGE. 

Concealed  as  the  eggs  are  beneath  several  layers  of  vegetable  tis- 
sue, it  is  impossible  to  examine  them  to  ascertain  the  exact  Length  of 
the  egg  stage  without  in  some  degree  interfering  with  the  naturalness 
of  the  accompanying  conditions.  The  beginning  of  the  stage  was 
easily  obtained  by  confining  female  weevils  with  uninfested  squares. 
Careful  dissections  were  then  made  of  the  squares  at  a  little  later 
than  what  was  found  to  "be  the  average  embryonic  period  at  that  sea- 
son. In  this  way  it  is  believed  the  range  of  error  was  reduced  to  a 
fraction  of  a  day  in  most  cases,  and  a  large  number  of  observations 
were  made  to  still  further  reduce  the  error. 

As  shown  by  Table  I,  553  observations  have  been  recorded  upon 
this  point,  the  majority  of  the  observations  being  made  in  the  fall  of 
1902.  Considering  the  temperatures  prevailing  at  the  four  periods 
studied,  it  appears  that  the  range  in  development  during  the  average 
season  at  Victoria,  Tex.,  has  been  included,  and  it  seems  probable 
that  from  these  temperatures  as  a  basis  the  length  of  the  egg  stage 
can  be  approximately  determined  for  any  season  and  for  any  locality 
within  the  p resent  area  of  infestation. 

Table  I. — Length  of  egg  stage  at  certain  periods. 


Period  of  examination. 

Number 
of  obser- 
vations. 

Mean 
tempera- 
ture for 
period. 

Average 
effective 

tempera- 
ture" 

Average 
length  of 

egg 

stage. 

1902. 
September  4-Oetoher  3.. 

385 

107 
36 

25 

°F. 
81 
73 
62 

72. 5 

of 

38 
L9 

32.  r> 

Days. 

2. 5  to    3 

October  7-November  13 

4      to    4.  ■"> 

November  27-Deceml>er  15 

11 

1JKK3. 
May  27-Jnne  5 

3..")  to    4 

Total 

563 

''3.  4  to    4.1 

«In  considering  the  influence  of  temperature  upon  the  weevils  it  has  been  assumed  that,  a-  has 
been  found  to  be  the  case  with  other  animals.  43°  P.  would  be  about  the  lowest  temperature  at 
which  the  weevils  would  be  active.  Temperatures  b  'low  that  point  would  have,  therefore,  no 
influence  upon  their  activity,  while  all  above  that  point  would.  For  this  reason  it  is  better  to 
speak  of  the  "effective  temperature.""  meaning  by  that  the  number  of  degrees  above  43°  F. 
Experiments  made  upon  the  influence  of  temperature  \ipon  the  activity  of  weevils  indicate 
that  this  is  very  near  the  correct  figure  for  this  insect. 

b  Weighted  average. 

The  extreme  range  observed  in  Table  II  in  the  length  of  this  stage 
is  from  two  to  fifteen  days,  while  the  average  period  for  the  whole 


22 


number  of  observations  is  but  three  and  six-tenths  days.  It  is  possi- 
ble that  the  embryo  can  undergo  an  even  greater  retardation  without 
losing  its  vitality. 

It  may  be  noted  here  that  drying  of  the  square  will  also  retard 
embryonic  development,  but  this  condition  does  not  occur  in  the  field. 

Table  II. — Range  in  length,  of  egg  stage. 


Number 

Length  of 

Number 

Length  of 

of  eggs. 

egg  stage. 

of  eggs. 

egg  stage. 

Days. 

Da  i/s. 

2 

2 

4 

5  to    6 

132 

2  to  3 

3 

8  to    9 

192 

I               3 

\       2  to  4 

5 

10  to  11 

15 

10  to  12 

42 

"     3  to  4 

4 

10  to  13 

ad 

3 

13  to  14 

yo 

1       3  to  5 

2 

13  to  15 

40 

4  to  5 

13 

/               5 

\       4  to  6 

The  length  of  the  egg  stage  in  bolls  does  not  appear  to  differ  greatly 
from  that  in  squares. 

HATCHING. 

While  still  within  the  egg  the  larva  can  be  seen  to  work  its  mandi- 
bles vigorously,  and  although  a  larva  has  never  been  seen  in  the  act 
of  making  the  rupture  which  allows  it  to  escape  from  the  egg,  it  is 
believed  that  the  rupture  is  first  started  by  the  mandibles.  The 
larva3  do  not  seem  to  eat  the  membranes  from  which  they  have 
escaped,  but  owing  to  the  extreme  delicacy  of  the  skin  it  is  almost 
impossible  to  find  any  trace  of  it  after  the  larva  has  left  it  and  begun 
feeding  on  the  square. 

HATCHING   OF   EGGS   LAID   EXTERNALLY. 

It  occasionally  happens  that  females  are  unable  to  force  an  egg  into 
the  puncture  prepared  to  receive  it  and  the  egg  is  left  on  the  outside 
of  the  square  or  boll.  Eggs  so  placed  usually  shrivel  and  dry  up  in  a 
short  time.  To  test  the  possibility  of  a  larva  making  its  way  into  a 
square  from  the  outside,  a  number  were  protected  from  drying.  Of 
the  19  eggs  tested,  6  hatched  in  from  two  to  three  days.  In  no  case, 
however,  was  the  young  larva  able  to  make  its  way  into  the  square 
and  it  soon  perished.  The  hatching  of  eggs  laid  externally  is  of  no 
importance,  since  the  larvae  must  perish  without  doing  any  damage. 

EATING   OF   EGGS   DEPOSITED    OUTSIDE. 

The  number  of  eggs  left  outside  increases  as  the  female  becomes 
weakened,  and  is  especially  noticeable  shortly  before  her  death.  The 
number  of  such  eggs  which  may  be  found  is  greatly  diminished  by  the 
following  peculiar  habit,  which  was  observed  manj7  times.  Occasion- 
ally it  appeared  that  the  puncture  which  the  female  had  made  for  the 
reception  of  an  egg  was  too  narrow  to  receive  it,  and  after  a  prolonged 
attempt  to  force  it  down  the  female  would  withdraw  her  ovipositor, 


28 

leaving  the  egg  .-n  i  he  surface.  She  would  i  hen  turn  immediately  and 
devour  the  egg.  After  that,  seeming  conscious  of  her  failure  and 
aware  of  tin*  cause  of  it,  she  would  proceed  to  find  and  enlarge  some 
what  the  cavity  pre^  iously  made.  When  this  was  completed  she  would 
at  tempi  bo  place  another  egg  therein.  The  second  attempt  was  usu 
ally  successful,  but  in  one  or  two  cases  a  female  was  seen  to  fail  several 
times,  and  iii  more  than  half  of  these  cases  she  ate  the  eggs,  as  has 
been  described. 

PERCENTAGE  OF  EGGS  THAT  HATCH. 

Definite  records  were  not  kept  upon  this  point,  but  in  the  many 
hundreds  of  eggs  followed  during  these  observations  very  few  failed 
to  hatch,  though  some  were  mueli  slower  in  embryonic  development 
than  were  others  laid  at  the  same  lime  and  by  the  same  female.  It 
is  the  writers'  general  impression  thai  less  than  1  percent  of  the  eggs 
are  infertile  or  fail  to  hatch. 

THE    LARVA. 
DESCRIPTION. 

The  young  larva,  upon  hatching  from  the  egg,  is  a  delicate,  white, 
legless  grub  of  about  1  nun.  (J-  inch)  in  length.  Kxcept  for  the 
brown  head  and  dark-brown  mandibles,  the  young  larva  is  atfirsl  as 
inconspicuous  as  the  egg  from  which  it  came.  As  it  feeds  and  grows 
it  continues  to  enlarge  a  place  for  itself  in  the  square  or  boll  until 
the  food  supply  has  become  exhausted  or  the  vegetable  tissues 
are  so  changed  as  to  be  unsuitable  for  food.  By  this  time,  as  a  rule, 
the  interior  of  the  square  lias  been  almost  entirely  consumed  and  the 
larval  eastings  are  spread  thickly  over  the  walls  of  the  cavity  (PI. 
Ill,  fig.  15).  This  layer  becomes  firmly  compacted  by  the  frequent 
turning  of  the  larva  as  it  nears  the  end  of  this  stage.  In  the  cell 
thus  formed  occur  the  great  changes  from  the  legless  grub  to  the  fully 
formed  and  perfect  beetle  (PI.  I,  figs.  7,  8,  and  0). 

Throughout  this  stage  the  bod}*  of  the  larva  preserves  a  vent  rally 
curved  crescentic  form  (PL  III,  fig.  10).  The  color  is  while,  modi- 
fied somewhat  by  the  dark  color  of  the  body  contents,  which  show 
through  the  thinner,  almost  transparent,  portions  of  the  body  wall. 
The  dorsum  is  strongly  wrinkled  or  corrugated,  while  the  venter  is 
quite  smooth.  The  ridges  on  the  dorsum  appear  t  )  be  formed  largel)T 
of  fat  tissue.  After  becoming  full-grown  the  larva  ceases  to  feed, 
the  alimentary  canal  becomes  emptied,  and  both  the  color  and  form 
of  the  larva  are  slightly  changed.  The  dark  color  disappears  from 
the  interior  and  is  replaced  by  a  creamy  tint  from  the  transforming 
tissues  within.  The  ventral  area  becomes  flattened,  and  the  general 
curve  of  the  bod}Ms  less  marked.  Swellings  may  be  seen  on  the  sides 
of  the  thoracic  region,  and  when  these  are  very  noticeable  pupation 
will  soon  take  place. 


24 

GROWTH. 

It  is  impossible  to  follow  the  growth  of  an  individual  larva  with- 
out interfering  so  greatly  with  its  normal  conditions  of  life  as  to 
make  the  observations  unreliable.  It  seemed  more  accurate  to  meas- 
ure larvae  of  approximately  known  ages.  In  these  measurements  the 
natural  curve  of  the  body  was  not  interfered  with,  but  the  measure- 
ment taken  across  the  tips  of  the  body.  In  this  way  it  was  found 
that  in  squares  during  the  hot  weather  the  length  of  the  body 
increases  quite  regularly  by  about  1  mm.  a  day.  As  it  becomes 
cooler  the  daily  growth  is  less.  In  bolls  which  grow  to  maturity  the 
rate  of  growth  is  less  and  the  length  of  the  growing  period  is  much 
greater.  Full-grown  larvae  vary  in  length  from  5  to  10  mm.  across 
the  tips  of  the  curve.  Larva^  of  normal  size  in  squares  average  from 
G  to  7  mm.  The  largest  larva?  are  developed  in  bolls  which  grow  to 
maturity  (PL  III,  fig.  10). 

MOLTS. 

To  accommodate  the  rapid  growth  of  the  larva  two  or  three  molts 
occur.  The  period  of  change  from  one  instar  or  stage  to  the  next  is 
so  short  that  the  chances  of  opening  a  square  at  just  the  right  time 
to  observe  the  process  are  very  small  indeed.  However,  it  has  been 
ascertained  beyond  question  that  two  molts  occur  before  the  larva 
reaches  half  its  growth.  The  first  occurs  at  about  the  second  day 
and  the  second  at  about  the  fourth  day.  Whether  a  third  molt 
occurs  before  rjupation  can  not  be  positively  stated ;  but  having  occa- 
sionally found  larva?  which  had  certainly  just  molted,  but  which  were 
much  larger  than  the  usual  size  at  the  second  molt,  the  writer  is  led 
to  suspect  that  three  larval  molts  nmy7  sometimes,  though  possibly 
the}7  do  not  always,  occur.  In  bolls  where  the  length  of  the  larval 
stage  is  often  three  or  four  times  as  great  as  that  usually  passed  in 
squares  it  seems  almost  certain  that  more  than  two  larval  molts  occur 
regularly.  Counting  only  the  first  two  molts  which  have  been  often 
fuii nd,  a  third  occurs  at  the  time  the  larva  pupates. 

PROCESS   OF  MOLTING. 

So  little  is  known  in  regard  to  the  molting  of  Curculionida?  that  the 
process  as  observed  is  here  recorded.  In  the  cases  observed,  starting 
at  the  neck,  the  skin  split  along  the  back,  and  was  then  pushed  down- 
ward and  backward  along  the  venter  of  the  larva.  The  cast  head 
shield  remained  attached  to  the  rest  of  the  skin. 

Immediately  after  casting  the  skin  the  head,  as  well  as  the  rest  of 
the  body  of  the  larva,  was  of  a  pearly-white  color.  The  tips  of  the 
mandibles  first  became  brown,  and  within  a  short  time  a  yellowish- 
brown  color  marked  the  entire  integument  of  the  head. 


Plate  II. 


1' 


Developmental  Stages  and  Work  of  the  Boll  Weevil. 

Fig.  13,  Two  boll  weevils  feeding  on  a  square,  natural  size:  fig.  14,  egg  isolated,  25  times  natural 
size;  fig.  15,  full-grown  larva  in  square,  natural  size:  iis.r.  16,  full-grown  larva  isolated,  natural 
size:  rig.  17.  pupa,  twice  natural  size:  fig.  18,  adult  just  transformed,  natural  size:  fig.19,  large 
larvae  in  large  boll,  two-thirds  natural  size:  fig.  20,  pupal  cell  in  boll,  broken  open,  twice  natural 

size.     (Original.  | 


LENGTH    «  'i     LARVA] 

Most  of  tho  observations  upon  the  larval  stage  wen  etween 

September  I  and  Decemlter  I  lh.-  temperatui  Lingdur 

mg  the  first  hah'  of  September  wan  as  high  a^  [g  ordinarily  exp< 
at    Victoria  during  midsummer,  and  th<  extremes  of  the 

average  season  may  bo  considered  as  having  •  d. 

The  time  of  egg  deposition  waseasil)  determined  by  exposing  unln- 
fested  squares  in  breeding  cages  containing  active  females.  The  time 
oi  hatching  of  the  larva  could  onlj'  be  found  bj  opening  the  sqti 
and  ii  was  bo  ascertained.  The  newly  hatched  larva  was  then  pi; 
in  a  small  <-a\  ii>  mad.-  bj  lifting  the  covering  on  the  Bide  of  a  freshly 
picked  square  and  removing  one  or  two  of  the  immature  anth< 
The  coverings  were  then  replaced  as  carefully  as  possible.  Another 
disturbance  was  necessary  to  determine  exactly  the  date  of  pupa- 
tion. Observations  made  in  this  waj  were  checked  by  others  using 
larva'  which  were  allowed  to  go  from  egg  deposition  to  pupation 
under  natural  conditions  and  without  disturbance  until  the  end  of 
the  larval  Btage  was  approximately  reached,  sine.'  the  sum  of  the 
times  found  for  the  various  stages  agrees  approximately  with  the 
known  length  of  the  immature  period  in  cases  where  nodisturban  e 
of  normal  conditions  occurred,  we  may  conclude  that  the  periods 
found  for  the  Larval  slap'  were  approximately  correct. 

Altogether  266  observations  were  recorded  upon  the  Length  of  this 
stage.  The  majority  of  the  observations  maybe  include'd  in  three 
groups,  and  when  thus  grouped  they  may  be  best  considered  in  relation 
to  the  effective  tempera  lure.  Table  III  presents  a  brief  summary  of 
these  groups: 

Table  III. — General  results  as  to  length  of  larval  stage  in  squares. 


Period  of  examination. 


1908. 

September  6  to  October  5 

September  26  to  October  21 

November  11  to  December  12  .  _ 


JSS.  USSR  ^;,r  £-g 
■HST  •ssr  $3K  --' 


3F. 
78. 
73. 


>F. 
35.7 
30.6 


195 
15 
15 


Day 8. 

6  to   9 

7  to  12 
20  to  30 


During  the  heat  of  summer  the  larval  stage  requires  approximately 
one  week.  This  time  appears  to  hold  so  long  as  the  mean  average 
temperature  remains  above  75°  F.  As  the  temperature  falls  below 
that  point  there  is  a  gradual  increase  in  the  length  of  this  stage.  The 
average  total  effective  temperature  required  during  hot  weather  by 
the  larval  stage  is  not  far  from  280°  F.  As  development  becomes 
retarded  by  colder  weather  the  average  total  effective  temperature 
required  to  complete  it  is  much  greater. 

These  facts  may  be  expressed  in  general  by  statin--  thai  during  the 
hottest  summer  weather  the  length  of  this  stage  Is  somewhat  Less  than 


26 

oik-  week.  Development  becomes  slower  as  the  temperature  falls, 
but  does  not  cease  altogether  so  long  as  cotton  can  live.  Even  frosts 
do  not  destroy  larvae  in  the  squares  and  bolls,  and  these  may  finish 
development  during  warmer  weather  after  the  frost  has  taken  place. 
The  length  of  the  larval  stage  in  bolls  is  as  a  rule  much  greater. 
If  the  boll  falls  when  small  the  increase  is  slight,  but  if  an  infested 
boll  grows  on  to  maturity  the  larval  stage  more  than  any  other  is  much 
extended.  Special  observations  upon  the  larval  stage  in  bolls  have 
not  been  made,  but  reckoning  from  the  known  length  of  the  whole 
developmental  period  in  maturing  bolls  we  may  conclude  that  the 
Larval  stage  can  not  be  less  than  six  or  seven  weeks. 

PUPAL    CELLS   IN    BOLLS. 

As  the  boll  approaches  maturity,  the  full-growu  larva  ceases  to  feed 
upon  the  drying  and  hardening  tissues  of  seed  and  fiber.  Its  excre- 
ment, more  or  less  mixed  with  lint,  becomes  firmly  compacted,  and  in 
the  drying  which  occurs  the  mass  forms  a  cell  of  considerable  firm- 
ness, within  which  pupation  and  the  subsequent  transformation  to 
the  adult  take  place  (PI.  Ill,  fig.  20).  These  pupal  cells  frequently 
include  a  portion  of  the  hull  of  a  seed,  but  the  writer  has  never  found 
a  large  larva  or  a  pupa  entirety  inclosed  within  a  single  cotton  seed. 
The  cells  described  are  shorter  and  thicker  than  seeds,  but  in  general 
appearance  there  is  considerable  resemblance  between  them  (PL  XI, 
fig.  4L).  Doubtless  these  cells  have  misled  some  into  the  statement 
that  they  have  found  weevils  in  cotton  seeds. 

PUPATION. 

The  formation  of  the  adult  appendages  has  gone  a  good  way  before 
the  last  larval  skin  is  cast.  The  wing  pads  appear  to  be  nearly  half 
their  ultimate  size.  The  formation  of  the  legs  is  also  distinctly  marked, 
and  the  old  head  shield  appears  to  be  pushed  down  upon  the  ventral 
side  of  the  thorax  by  the  gradual  elongation  of  the  forming  proboscis. 
Finally  the  tension  becomes  so  great  that  the  tightly  stretched  skin  is 
ruptured  over  the  vertex  of  the  head,  and  it  is  then  gradually  cast  off, 
revealing  the  delicate  white  pupa.  The  cast  skin  frequentlj'  remains 
for  some  time  attached  to  the  tip  of  the  abdomen. 

THE    PUPA. 

When  this  stage  is  first  entered  the  insect  is  a  very  delicate  object 
both  in  appearance  and  in  reality.  Its  color  is  either  pearly  white 
or  cream.  The  sheaths  for  the  adult  appendages  are  fully  formed  at 
the  beginning  of  the  stage  and  no  subsequent  changes  are  apparent 
except  in  color  (PL  I,  figs.  5  and  6).  The  eyes  first  become  black, 
then  the  proboscis,  elytra,  and  femora  become  brownish  and  darker 
than  the  other  parts  (PL  III,  fig.  17). 


29  i 

The  final  molt  requires  about  thirt}  minutes.  The  skin  splits  open 
over  the  front  of  the  head  and  slips  down  along  the  proboscis  and 
hack  over  the  prothorax.  The  skin  clings  to  the  antennae  and  the  tip 
of  the  proboscis  i  ill  after  the  dorsum  has  been  uncovered  and  the  legs 
kicked  free.  Then  by  violently  pulling  upon  the  skin  with  the  fore 
legs  first  the  tip  of  tli<'  snout  and  then  the  antennas  are  freed,  and 
finally  the  shrunken  and  crumpled  old  skin  is  kicked  off  the  tip  of 
i  he  abdomen  by  the  hind  Legs. 

LKNGTB  OF  PUPAL  STAGE. 

The  length  of  this  stage  is  more  easily  determined  than  thai  of  any 
other.  It  seemed  to  make  Little  difference  in  the  time  whether  the 
pupa'  were  allowed  to  remain  in  the  squares  or  removed  therefrom. 
Considerable  variation  in  the  Length  of  this  stage  exists  among  indi- 
viduals of  the  same  generation  and  even  between  offspring  of  the 
same  female  and  from  eggs  laid  on  the  same  day.  The  period  of 
investigation  ranged  from  July  to  December,  so  thai  the  extremes  of 
the  season  are  included.  Altogether  over  450  observations  were  made 
upon  the  Length  of  this  stage.  Nearly  all  of  these  are  included  in 
Table  IV,  which  shows  a  summary  of  the  results. 


Table  IV.  —  Tabular  arrangement  of  observations  upon  the  length  of  pupal  stage 

in  squares. 


K*  W  ttsr  tefe 

vat!,,,.'.  °«£^  ,'f  "4,.  tempera-ltompBr*. 


Period  <>t'  examination. 


Average     Total 


iper 
tnre. 


tare. 


1902. 

July  6  to  31 -. 161 

September  16  to  October  3 81 

September  24  to  October  28 lf>7 

November  2  to  13 I  2S) 

December  2  to  29 4 


1></I/S. 

2  to   5 

3  to   7 

4  to   8 

5  to   6 
10  to  16 


J>(ll/s. 

3.5 

5. 2 
6.0 
5.6 

14.5 


°  F. 
39.  65 

36.05 

31.1 
26.2 
18.55 


138.8 
187.5 
186. 1 
1 40.  7 
269.0 


It  should  be  noted  in  connection  with  Table  IV  that  the  observa- 
tions made  in  November  were  during  a  period  of  rather  warm  weal  her 
and  that  the  temperature  records  for  that  time  are  incomplete.  It  is 
likely  thai  the  average  effective  temperature  given  for  that  period 
might  he  different  were  the  records  complete. 

The  average  length  of  this  period  during  hot  weather  is  from  three 
to  four  days,  and  the  period  increases  as  the  cool  fall  weather 
approaches  to  a  maximum  of  about  fifteen  days. 

A  comparison  of  Tables  I,  III,  and  IV  shows  that  the  decrease  in 
temperature  affects  each  stage  in  very  nearly  the  same  proportion. 
In  each  case  the  maximum  recorded  length  of  any  stage  is  about  four 
times  its  minimum,  and  the  great  retardation  in  each  ease  occurs 
somewhere  between  60°  and  70°  F.  of  mean  average  temperature,  or 
17°  to  27°  F.  of  effective  temperature.  Even  greater  retardation 
occurs  during  the  winter  season. 


28 

The  Length  of  the  pupal  stage  in  large  bolls  has  not  been  deter- 
mined. It  appears  to  be  Longer  than  in  squares,  but  it  certainly  can 
not  occupy  the  same  proportional  part  of  the  entire  developmental 
period  that  it  does  in  squares. 

EFFECT   OF   BURYING    SQUARES   UPON   PUPATION    AND   THE    ESCAPE    OF 

ADULTS. 

The  experiments  made  upon  this  point  were  designed  to  ascertain 
the  value,  if  any,  in  the  plowing  under  of  squares  as  a  means  of 
destroying  the  larvae  and  pupa?  infesting  them.  But  few  experiments 
seemed  necessary  to  demonstrate  the  futility  of  this  operation  alone 
as  a  means  of  controlling  the  weevil. 

Squares  which  were  known  to  be  infested  with  about  half-grown 
larva*  were  placed  in  glass  jars  and  covered  with  several  inches  of 
quite  dry  and  fairly  well  pulverized  earth.  When  examination  was 
made  it  was  found  that  pupation  had  taken  place  normalh7  while  the 
squares  were  buried  under  from  2  to  5  inches  of  dirt.  In  no  case 
was  pupation  prevented,  though  a  few  weevils  did  not  leave  the 
squares  after  having  become  adult.  Altogether  about  100  squares 
were  thus  buried,  and  from  them  over  75  weevils  emerged. 

In  a  portion  of  the  preceding  tests  careful  examination  was  made 
to  ascertain  how  far  toward  the  surface  the  newly  emerged  weevils 
had  succeeded  in  getting  before  they  perished.  It  should  be  noted 
that  these  weevils  had  never  fed,  and  they  would  have,  therefore,  less 
strength  and  endurance  than  such  fully  hardened  adults  as  might  be 
buried  in  the  ordinary  processes  of  field  cultivation.  Furthermore, 
the  soil  used  was  of  finer  texture  and  more  compactly  settled  than  it 
would  be  in  the  field.  Twenty-seven  weevils  were  found  in  this  exam- 
ination, their  location  varying  from  the  bottom  of  the  jar  to  their 
having  escaped  through  1  inches  of  soil.  A  weighted  average  shows, 
however,  that  each  weevil  had  made  its  way  upward  through  2  inches 
of  dirt.  AVe  may  infer,  therefore,  that  had  these  squares  been  buried 
under  less  than  2  inches  of  fairly  well  pulverized  earth,  as  would  be 
the  case  from  field  cultivation,  but  a  small  percentage  of  them  would 
have  failed  to  make  their  way  out.  As  it  Avas,  full}'  three-fourths  of 
those  leaving  the  squares  made  their  way  out  through  more  than  2 
inches  of  dirt. 

In  1896  Mr.  C.  L.  Marlatt  noted  that  "the  weevils  can  escape  from 
loose  soil  when  buried  to  a  depth  of  3  inches,  but  when  artificially 
embedded  8  inches  in  moist  soil  they  are  unable  to  extricate  them- 
selves, as  shown  by  test  experiment."  Quite  extensive  experiments 
are  now  being  made  at  Victoria  to  test  the  ability  of  the  fully  fed 
adult  weevils  to  escape  after  being  buried  at  various  depths  and  in  soil 
containing  various  percentages  of  water.  That  the  moisture  content 
exerts  a  great  influence  upon  the  texture  of  the  soil  is  especially 
noticeable  in  the  black  bottom  lands  of  the  Texas  cotton  belt.     While 


2 1 1 

the  results  of  these  experiments  ma}  furnish  reasons  for  changing  our 
conclusions  upon  tins  point,  ili«'  present  indication  is  that  the  bene 
iici.il  effect  of  thorough  cultivation  Lies  in  th<-  direct  influence  which 
that  practice  exerts  upon  the  steady  and  rapid  growth  of  the  cotton, 
thus  favoring  the  production  <>f  squares,  1 1 1 « *  setting  of  bolls,  and  the 
early  maturity  of  the  crop  rather  than  in  the  direct  destruction  of  the 
weevils  by  burying  them  either  while  in  the  squares  or  after  the}  liave 
become  adult. 

THE   ADULT. 
BEFORE    EMERGENCE. 

Immediately  after  its  transformation  from  the  pupa  the  adult  is 
very  Light  in  color  and  comparatively  soft  and  helpless.  The  probos- 
cis is  darkest  in  color,  being  of  a  yellowish  brown;  tin1  pronotum, 
tibiae,  and  tips  of  the  elyt  ra  come  next  in  depth  of  coloring.  The  ely- 
tra are  pale  yellowish,  as  are  also  the  femora.  'Die  month  parts,  claws, 
and  the  teeth  upon  the  inner  side  of  the  fore  femora  are  nearly  black. 
The  body  is  soft  and  the  young  adult  is  unable  to  travel  (PL  III, 
fig.  18),  consequently  this  period  is  passed  where  pupation  occurs. 
Usually  two  or  more  days  are  required  to  attain  the  normal  coloring 
and  the  necessary  degree  of  hardness  to  enable  the  adult  to  make  its 
escape  from  the  square  or  cell. 

EMERGENCE. 

The  normal  method  of  escape  from  squares  and  small  bolls  is  by 
cutting  with  its  mandibles  a  hole  just  the  size  of  the  weevil's  body 
(PL  IV,  fig.  21).  In  large  bolls  the  escape  of  the  weevil  is  greatly 
facilitated  by  the  natural  opening  of  the  boll  (PL  IV,  fig.  22).  Often 
the  pupal  cell  is  broken  open  by  the  spreading  of  the  carpels,  and 
when  this  is  the  case  the  pupa,  if  it  has  not  already  transformed, 
becomes  exposed  to  the  attack  of  enemies  or,  what  is  probably  a  more 
serious  menace,  the  danger  of  drying  so  as  to  seriously  interfere  with 
a  successful  transformation.  If  the  cell  remains  unbroken  the  weevil 
always  escapes  by  the  path  of  least  resistance,  cutting  its  way  through 
as  in  the  case  of  a  square  (PL  IV,  tig.  20).  The  material  removed 
does  not  appear  to  be  eaten,  but  is  rather  cast  aside  and  left  within 
the  cell  as  a  mass  of  line  debris. 

CHANGES   AFTER   EMERGENCE. 

At  the  time  of  emergence  the  weevils  are  comparatively  soft,  and 
they  do  not  attain  their  final  degree  of  hardness  for  some  time  after 
they  have  begun  to  feed.  If  they  never  feed  they  never  harden. 
The  color  of  the  chitin  is  of  an  orange  tinge  at  the  time  the  weevils 
leave  the  squares  or  bolls,  but  after  exposure  for  some  time  it  turns 
to  a  dark  chocolate  browm.  The  development  of  the  hair-like  scales 
is  probably  entirely  checked  by  the  drying  of  the  chitin,  but   the 


30 

darkening  of  the  ground  color  makes  the  scales  more  apparent,  and 
thus  gives  the  impression  of  further  development  after  emergence  has 
taken  place. 

SIZE    OF   WEEVILS. 

Size  of  boll  weevils  is  an  especially  variable  quantity,  and,  as  usual, 
varies  almost  directly  in  proportion  to  the  abundance  of  the  larval 
food  supply  and  the  length  of  the  period  of  larval  development.  The 
ex1  remes  arc  so  great  that  the  smallest  and  largest  weevils  would  be 
thought  by  one  not  thoroughly  familiar  with  them  to  be  of  entirely 
different  species.  So  far  as  dimensions  may  convey  an  idea  of  the 
size,  we  may  say  that  the  weevils  range  from  3  to  8  mm.  (I  to  J  inch) 
in  length,  including  the  proboscis  extended,  and  from  1  to  3  mm.  ( Jz 
to  i  inch)  in  breadth  at  the  middle  of  the  body.     (See  PL  I,  fig.  1.) 

RELATION    OF   SIZE   TO   FOOD    SUPPLY. 

The  smallest  weevils  are  developed  from  squares  which  were  very 
small,  and  which,  for  some  reason,  either  of  plant  condition  or  of 
additional  weevil  injury,  fell  very  soon  after  the  ev;g  was  deposited. 
The  supply  of  food  was  not  only  small,  but,  owing  to  the  immaturity 
of  the  pollen  sacs,  its  quality  was  also  poor.  Normally  squares  con- 
tinue to  grow  for  a  week  or  more  after  eggs  are  deposited  in  them,  and 
such  squares  produce  the  weevils  of  average  size  and  color. 

The  largest  weevils  are  produced  in  bolls  which  grow  to  maturity. 
In  them  the  food  supply  is  most  abundant,  and  the  period  of  larval 
development  is  several  times  as  long  as  it  is  in  squares.  Possibly 
these  differences  in  size  may  be  better  shown  by  a  summary  of 
observations  which  were  made  upon  the  weight  of  adults. 

WEIGHT   OF   ADULTS. 

The  weevils  used  in  these  experiments  were  bred  to  insure  their 
coming  from  the  proper  source.  After  emergence  they  were  fed  for 
some  time  to  bring  them  up  to  their  normal  weight. 

Table  V. — Summary  of  iceigJit  of  Weevils, 


Source  of  weevils. 


Bred  from  picked  small  squares  . . 
Bred  from  average  fallen  squares 
Bred  from  large  bolls 


Total 

Average  weight  per  weevil,  all  sources 


*»*«■  t33f.e 


Grain. 

ii.  in:, 
.231 
.268 


162 


36.825 
.227 


It  should  be  noted  that  these  figures  do  not  nearly  represent  the 
weight  of  the  extremes  in  size,  but  they  do  indicate  the  difference  in 
the  average  weevil  of  each  class. 


61 

COLOR. 

Color  is  \ci\  often  a  variable  character  In  Insects,  and  the  l>oll 
weevil  presents  considerable  range  in  this  respect.  Whatever  in  flu 
ences  tin*  size  <»r  the  larva  affects  directly  the  Bize  of  the  adult,  ;in<l  it 
is  noticeable  that  weevils  of  the  same  size  are  also,  as  a  rule,  closely 
alike  in  color,  in  general,  the  smaller  the  size  of  the  weevil  the 
darker  brown  is  its  color;  the  largesl  weevils  arc  Lighl  yellowish 
brown.  Between  these  two  extremes  arc  the  majority  of  average- 
sized  weevils,  which  are  either  of  a  gray-brown  or  dark  yellow-brown 
color.  Weevils  developing  in  iarge  bolls,  having  an  abundant  food 
supply  and  a  developmental  period  averaging  more  than  twice  thai 
of  weevils  in  squares,  arc  Larger  in  size  and  more  yellowish  in  color 
than  are  those  from  squares. 

The  principal  reason  for  the  variation  in  color  lies  in  the  degree  of 
development  of  the  minute  hair-like  scales,  which  are  much  more 
prominently  developed  in  the  Large  than  in  the  small  specimens, 
although  the  color  of  old  specimens  is  often  changed  by  the  rubbing 
off  pf  the  scales.  The  scales  are  yellow  in  color,  while  the  ground 
color  of  the  chitin  bearing  them  is  a  dark  brown  or  reddish  brown. 
When  the  scales  are  but  slightly  developed,  as  seems  to  be  the  case 
with  small  weevils  produced  from  underfed  larvae,  the  dark-brown 
ground  color  is  predominant,  while  in  the  case  of  large  weevils  pro- 
duced from  larva*  having  abundant  food  and  a  long  period  of  devel- 
opment the  scales  are  largely  produced  and  give  the  strong  yellow 
tone  to  the  color  which  is  characteristic  of  them. 

The  development  of  the  scales  appears  to  take  place  mostly  after 
the  adult  weevil  has  become  quite  dark  in  color  but  before  it  becomes 
fully  hardened.  They  seem,  therefore,  to  be  a  sort  of  non-essential 
aftergrowth  which  depends  upon  the  surplus  food  supply  remaining 
after  the  development  of  the  essential  parts  of  the  wreevil  structure. 

SIZE   AND   COLOR  NOT   INDICATIVE    OF   SEX. 

Eminent  coleopterists  have  studied  the  boll  weevil  most  carefully 
with  the  purpose  of  discovering  some  external  character  by  which  the 
sexes  could  be  distinguished,  but  all  have  failed  to  find  an}-  reliable 
points  of  distinction.  The  writer  therefore  does  not  hesitate  to  own 
that  he  also  has  failed  to  find  any  reliable  character  for  the  distinc- 
tion of  the  sexes.  Many  persons  have  the  idea  that  the  small  dark 
weevils  are  males  and  the  larger  and  lighter-colored  brownish-yellow 
weevils  are  females.  This  idea  is  a  mistaken  one.  In  general  it  is 
probably  true  that  the  males  are  slightly  smaller  than  the  females, 
but  judging  from  determinations  of  the  sex  of  many  hundreds  of 
weevils  it  may  be  stated  positively  that  size  and  color  are  characters 
which  are  related  to  food  supply  and  length  of  the  period  of  develop- 
ment and  are  not  indications  of  sex.  The  sexes  seem  to  be  about 
equally  represented  among  the  smallest  as  well  as  the  largest  weevils. 


32 

Characters  commonly  used  to  separate  the  sexes  in  the  family  Cur- 
culionidaB  are  not  distinctive  in  this  species.  As  a  rule  the  antennas 
arc  inserted  nearer  the  tip  of  the  snout  in  the  male  than  in  the  female. 
This  character  is  variable  among  boll  weevils;  and  though  a  large 
number  of  accurate  measurements  might  show  that  a  slight  difference 
generally  exists,  it  is  too  inconspicuous  a  character  to  be  of  general 
use.  With  most  species  the  top  of  the  rostrum  of  the  male  is  rougher 
than  is  thai  of  the  female.  However  it  maybe  with  other  species, 
there  is  but  little  if  any  difference  in  this  respect  between  the  young 
ad  lilts  of  the  boll  weevil.  As  the  individuals  become  older  the  greater 
activity  of  the  females  serves  to  wear  the  roughness  from  the  top  of 
the  rostrum,  and  thus  gradually,  as  a  result  of  different  habits,  this 
character  becomes  more  distinctive.  In  less  than  half  of  the  boll 
weevils,  however,  is  this  character  sufficiently  noticeable  to  separate 
the  sexes.  The  terminal  segment  of  the  abdomen  shows  no  external 
difference  in  either  sex,  although  in  many  weevils  important  charac- 
ters are  there  found. 

PROPORTIONS   OF   THE   SEXES. 

No  reliable  secondary  sexual  characters  having  as  yet  been  discov- 
ered, the  certain  determination  of  sex  therefore  rests  solely  upon  the 
primary  characters,  thus  requiring  a  certain  amount  of  dissection  in 
each  case.  Such  determinations  have  been  made  upon  large  numbers 
of  weevils  taken  in  the  field  and  upon  many  bred  in  the  laboratory  at 
various  seasons  of  the  year.  The  results  are  briefly  summarized  in 
Table  VI. 

Table  VI. — Proportions  of  the  sexes. 


Number 
of  males. 


Number 
of  fe- 
males. 


Season  of  1902,  both,  bred  and  from  field 

Hibernated  weevils,  1902-3  - 

First  generation,  1903 

Bred  weevils,  1903 

Field  weevils,  midsummer,  1903 


Total 


240 

269 

43 

45 

52 


649 


260 
174 
32 
33 


sS8 


From  these  1,207  determinations  it  appears  that  males  are  somewhat 
more  numerous  than  females,  the  percentage  being  nearly  54  of  males 
to  46  of  females.  It  is  noticeable,  however,  that  the  only  season  at 
which  a  preponderance  of  males  occurs  is  during  late  fall.  If  we 
exclude  the  figures  for  hibernated  weevils  for  a  moment,  we  find  that 
the  totals  for  the  balance  of  the  season  are  remarkably  close  for  the 
two  sexes,  being  380  males  and  384  females.  It  seems  safe  to  say, 
therefore,  that  the  sexes  are  practically  equal  in  numbers  except  that 
more  males  than  females  seem  to  be  found  among  hibernating  weevils. 
It  may  be  that  the  retardation  of  development  due  to  approaching 


Breeding  Jar  and  Method  of  Escape  of  Adults  from  Squares  and  Bolls. 

Fig.  21,  Emergence  hole  made  by  weevil  in  square,  natural  size:  fig.  22,  weevil  escaping  nor- 
mally from  boll,  two-thirds  natural  size:  li.tr.  23,  apparatus  used  in  breeding  weevils,  one-fourth 
natural  size:  fig.  24,  larva  destroying  the  ovary  and  preventing  the  bloom  in  large  squares, 
natural  size:  fig.  'J.'),  leaf  fed  upon  by  weevils  in  confinement,  one-half  natural  size:  ii.ar.  26, 
emergence  hole  of  weevil  from  boll  which  never  opened,  two-thirds  natural  size.     (Original.) 


Fig.  27.— Larva  in  Square,  Ovary  Untouched,  Natural  Size.    'Original.'. 


Fig.  28.— Large  and  Small  Larv/e  in  Boll,  Two-thirds  Natural  Size.    'Original.) 


88 

cold  weather  favors  the  development  <>f  males.  Nol  only  was  there  a 
larger  number  of  males  than  of  females  taken  In  December,  L902,  but 
there  were  also  more  males  than  females  taken  in  the  field  in  the  spring 
of  L903  among  the  hibernated  weevils  which  lived  through  the  winter. 
According  t<>  the  determinations  made,  64  per  cent  <>f  tin-  259  weevils 
dying  during  the  winter  were  males  and  56  per  ecu  i  of  the  weevils  liv- 
ing through  the  winter  were  also  males,  since  ii  appears  thai  females 
require  fertilization  in  the  spring  before  they  begin  to  deposit  eggs, 
the  preponderance  of  males  at  that  time  acts  as  a  provision  to  insure 
i he  propagat  i<m  <>f  i he  species. 

LENGTH    OF    LIFE    UPON    SQUARES. 

The  observations  made  along  this  line  may  be  divided  into  eight 
groups,  each  dealing  with  some  special  food  condition  or  class  of 
weevils.  For  the  confinement  of  weevils  in  the  Laboratory  the  most 
satisfactory  apparatus  tried,  both  for  convenience  in  handling  and  for 

the  maintenance  of  favorable  conditions  for  the  weevil,  was  made  up 
as  follows:  A  4  or  5  inch  shallow  earthen  saucer,  such  as  is  used  with 
flowerpots,  was  tilled  with  soil,  which  was  kept  fairly  moist.  Over 
tins  was  placed  a  fresh  cotton  leaf,  which  conserved  the  moisture  from 
the  soil,  but  never  became  wet,  and  kept  both  weevils  and  squares 
clean,  besides  facilitating  the  handling  necessary  to  frequent  renewr- 
als  of  the  food  supply  and  the  consequent  transference  of  the  weevils. 
The  rest  of  the  cage  was  formed  by  an  ordinary  lantern  globe  cov- 
ered at  the  top  by  cheese  cloth  held  firmly  in  place  by  a  rubber  band. 
With  this  apparatus  weevils  could  be  readily  observed  without  dis- 
turbing them,  and  food  supplied  was  kept  in  good  condition  and  could 
be  easily  renewed,  while  there  were  no  cracks  to  hide  in  or  to  allow 
weevils  to  escape  (PL  IV,  fig.  23).  The  moisture  of  the  soil  and 
fresh  leaf  covers  were  renewed  as  needed.  Clean  squares  were  sup- 
plied each  day,  and  the  actual  number  of  egg  and  feeding  punctures 
recorded  upon  numbered  slips  kept  with  each  cage.  The  sex  of  each 
weevil  was  also  determined  and  noted  upon  its  death,  thus  giving  an 
accurate  record  of  the  number  and  sex  of  weevils  responsible  for  the 
punctures  recorded.  Most  of  the  weevils  used  were  bred,  so  that  the 
exact  length  of  their  lives  is  known.  Length  of  life  refers  only  to 
adult  life  from  the  time  of  emergence  from  the  square  or  boll  to  the 
death  of  the  weevil.  Many  weevils  brought  in  from  the  field  were 
under  observation  in  the  laboratory  for  periods  sufficiently  long  to 
justifjr  the  inclusion  of  the  results  obtained  from  them  with  those  of 
weevils  which  were  bred.  Obviously  the  time  these  were  under 
observation  does  not  represent  their  true  length  of  life;  therefore  the 
inclusion  of  both  results  renders  the  averages  obtained  the  more  con- 
servative. 

21739— No.  45—04 3 


34 


Table  VII. — Length  of  life  of  weevils  upon  squares. 


Males. 


Number.  *™^° 


Weevils  placed  in  hibernation  Dec.  15, 1902:  living  Apr.  15. 

UXtt... 23 

Hibernated  weevils  taken  spring,  1903;  estimated  adult 

Dec.  15,  1902 66 

f  OQ 

Hibernated  weevils,  from  time  of  feeding  in  1903 %~ 

First  generation,  bred |  30 

Third  generation,  bred 18 

Fifth  generation,  bred |   •  9 

Totals  and  weighted   averages,  including    hibernation 

period 146 

Totals  and  weighted  averages,  npt  including  hibernation  I 

period 147 

Entire  length  of  life,  hibernated  weevils  only J  89 


180 
223 


151 


71 
212 


Females. 


Number.  Avenge 


111 


112 
67 


171 

220 


148 


64 

210 


Whether  we  include  the  time  of  hibernation  or  not,  it  appears  from 
the  averages  of  156  hibernated  weevils  that  those  which  winter  suc- 
cessfully are  longer  lived  than  any  following  generation,  as  their 
active  life  in  spring  averaged  fully  80  days  for  males  and  70  for 
females.  Probably  the  greater  activity  of  the  first  generation  may 
account  for  their  somewhat   shorter  life.      The  average  active  life 


period  for  all  generations  is  probably  not  far  from 
and  61  days  for  females. 


1  davs  for  males 


LENGTH  OF  LIFE  ON  BOLLS  ALONE. 

As  weevils  appear  to  feed  freely  on  bolls  in  the  field  after  the  period 
of  maximum  infestation  has  been  reached  (PI.  I,  fig.  10),  these  tests 
were  made  to  determine  whether  they  might  be  able  to  live  normally 
with  no  other  food. 

A  number  of  weevils  were  placed  upon  bolls  as  soon  as  they  became 
adult.  Others  which  had  first  been  fed  upon  squares  were  given  bolls 
after  they  had  become  hard  and  had  shown  themselves  to  be  in  a  nor- 
mally healthy  condition.  Of  the  total  37  weevils  thus  tested,  16  were 
males  and  21  were  females.  The  males  showed  an  average  length  of 
life  of  19.7  days,  while  the  females  survived  for  only  15.2  days.  This 
is  a  much  shorter  period  than  the  normal  length  of  life  upon  squares 
for  either  sex. 


LENGTH    OF   LIFE    ON   COTTON   LEAVES   ALONE. 

To  determine  whether  they  could  live  upon  the  foliage  of  cotton 
alone  69  newly  transformed  weevils  were  at  the  1st  of  October,  1902, 
placed  upon  fresh  leaves,  which  were  renewed  at  frequent  intervals. 
During  the  first  three  weeks  52  of  these  weevils  (21  male  and  31 
female)  died,  leaving  17  alive  and  well;  11  of  these  were  then  returned 
to  squares  and  6  continued  upon  the  leaves.  Of  these  6,  3  lived  to  be 
81  days  old  and  were  then  intentionally  killed  for  dissection.     The 


35 

average  length  of  Life  of  those  kept  entirely  upon  leaven  was  over  30 
days.  These  results  show  clearij  the  ability  of  main  of  the  weevils 
to  live  upon  foliage  alone  in  fields  In  which  fall  grazing  ifl  practiced 
until  ii  becomes  sufficiently  cold  for  them  to  go  into  winter  quarters 
(see  PL  [V,  Bg.  25). 

LENGTH    OF    LIFE    with    SWEETENED    WATEB    \M>    WITH    MOLASSES. 

So  mnch  has  been  said  about  the  attraction  of  molasses  for  the 
uir\  Ha  thai  tests  were  made  with  a  cheap  grade  of  molasses  diluted 
whli  from  20  to  25  parts  of  water  to  see  whether  this  solution  really 
served  them  as  food.  The  weevils  used  were  jusi  adult  and  had  taken 
no  other  food.  They  fed  quite  readily  upon  the  solution,  remaining 
quietly  with  their  snouts  in  the  water  for  from  a  few  minutes  to  an 
hour  and  a  half  at  a  time.  The  solution  did  not  seem  to  draw  them 
from  any  distance,  but  as  soon  as  a  Aveevil  came  to  it  it  would  stop  to 
drink.  Feeding  or  drinking-  took  place  daily  or  often er  until  the 
death  of  the  weevils.  The  average  length  of  life  for  the  12  weevils 
used  was  a  little  less  than  (5  days. 

As  weevils  without  food  but  with  water  lived  an  average  of  5£ 
days,  the  conclusion  is  that  a  solution  of  molasses  1  to  water  25  parts 
does  not  serve  the  weevil  as  food,  since  it  does  not  noticeably  prolong 
life. 

Six  weevils  just  emerged  kept  upon  undiluted  molasses  showed  a 
greater  length  of  life,  these  dying  at  an  average  age  of  1H  days. 

LENGTH    OF   LIFE   WITHOUT   FOOD,  BUT    WITH   WATER. 

These  observations  were  made  during  August  as  a  check  upon  those 
without  water.  The  8  weevils  used  were  just  adult  and  had  never 
fed.  Each  weevil  drank  for  one  or  two  minutes  at  least  once  each 
day  so  long  as  it  lived.  All  died  at  nearly  the  same  time,  having 
lived  for  an  average  of  about  5^  days.  As  those  without  water  lived 
an  average  of  5  days,  it  appears  that  access  to  water  in  the  absence 
of  food  does  not  materially  increase  the  length  of  life  of  the  starving 
weevils. 

LENGTH   OF   LIFE    WITHOUT   FOOD    OR   WATER. 

Three  series  of  observations  were  made  along  this  line.  In  the  first 
the  weevils  used  were  taken  immediately  after  emergence  and  never 
allowed  to  feed.  Fifty  weevils  were  tested  in  this  way  during  July 
and  August  and  showed  an  average  length  of  life  of  5  days  from  the 
date  of  emergence.  A  few  lived  as  long  as  8  or  9  days.  These  never 
acquired  as  dark  a  color  nor  as  great  a  degree  of  hardness  as  is  normal. 

In  the  second  series  the  15  weevils  used  were  7  weeks  old  and  full- 
fed  at  the  time  of  beginning  the  test.  These  showed  an  average  length 
of  life  of  slightly  over  6  days,  the  range  being  from  5  to  9  days.  These 
weevils  were  tested  during  the  latter  half  of  November,  and  the  late- 


36 

aesfi  of  the  Reason,  together  with  the  fall-fed  condition  of  the  weevils, 
seemed  to  promise  a  considerably  Longer  period  than  6  days. 

In  the  third  series  the  L8  weevils  used  were  1  month  old  and  full* 
fed  at  the  beginning  of  the  test  in  the  middle  of  November.  The  con- 
ditions in  this  series  were  as  in  the  series  preceding,  with  the  excep- 
tion that  an  abundance  of  two  species  of  grass  taken  from  cotton 
fields  was  included.  These  weevils  showed  an  average  length  of  life 
of  nearly  1\  days,  ranging  from  3  to  10  days.  The  weevils  made  no 
effort  to  feed  upon  the  grass,  so  the  slightly  longer  life  period  must 
be  due  to  other  causes. 

CANNIBALISM. 

It  is  hardly  proper  to  speak  of  cannibalism  as  a  food  habit  of  the 
boll  weevil,  but  the  facts  observed  may  well  be  recorded  here.  Under 
the  impulse  of  extreme  hunger  weevils  have  several  times  showed  a 
slight  cannibalistic  tendency. 

Seven  beetles  were  confined  in  a  pill  box  without  food.  On  the 
third  day  6  only  Avere  alive.  Of  the  seventh  only  the  hardest  chitin- 
ized  parts  (head,  proboscis,  pronotum,  legs,  and  elytra)  remained,  the 
softer  parts  having  been  eaten  by  the  survivors. 

In  another  box  containing  12  adults  the  leaf  supplied  for  food  was 
insufficient,  and  on  the  fourth  day  8  were  dead,  4  were  partly  eaten, 
and  others  had  lost  one  or  more  legs  each. 

In  another  case  a  few  young  adults  and  a  number  of  squares  con- 
taining pupae  were  placed  in  a  box  together  with  a  few  fresh  squares 
to  serve  as  food  for  the  adults.  When  the  box  was  opened  after  a 
number  of  days,  one  "reddish-brown"  adult  was  found  having  its 
elytra  eaten  through  and  most  of  its  abdomen  devoured.  In  spite  of 
tins  mutilation  the  victim  was  still  alive  and  kicking  slowly.  The 
squares  were  still  fresh  and  fit  for  food,  so  that  this  is  really  the  clear- 
est case  of  cannibalism  observed. 

Frequent!}"  more  than  one  larva  hatches  in  a  square,  and  when  this 
is  the  case  a  struggle  between  them  is  almost  certain  to  take  place 
before  they  become  full  grown.  Many  cases  have  been  observed  in 
which  squares  contained  one  living  and  one  or  more  smaller  dead 
larva?,  while  in  a  few  cases  the  actual  death  struggle  was  observed. 

HABITS. 

Among  the  habits  of  any  insect  of  economic  importance,  the  first 
for  careful  study  are  those  relating  to  its  food,  and  secondly  those 
connected  with  its  propagation.  The  study  of  the  life  history  of  the 
boll  weevil  has  revealed  no  especially  vulnerable  point,  but  rather  the 
important  fact  that  in  all  its  stages  it  is  better  protected  against  the 
attacks  of  enemies  and  the  ordinarily  effective  remedies  recommended 
by  the  economic  entomologist  than  any  other  insect  which  has  ever 
threatened  the  production  of  any  of  the  great  staple  crops  of  this 


87 

count  i\ .  Naturally,  then,  we  must  needs  turn  to  a  Btudj  of  the  habits 
of  the  pest  to  point  1 1 1 « *  waj  i<»  means  i>\  which  either  ii  may  be  itself 
destroyed  or  its  great  destructiveness  prevented, 

FOOD  HABITS. 
L  \K\AL. 

1 1  is  plainly  the  intention  of  the  mother  weevil  to  deposit  her  egg  so 
that  t li«'  larva  upon  hatching  will  find  itself  surrounded  by  an  abun- 
dance of  favorable  food.  In  thegreal  majority  of  cases  this  food  con- 
sists principally  of  immature  pollen.  This  is  the  lirst  food  of  the  larva 
which  develops  in  a  square,  and  it  must  be  both  delicate  and  nutritious. 
Often  a  Larva  will  eat  its  way  entirely  around  a  square  in  its  pursuit 
of  this  food.  In  most  eases  the  larva  is  about  half  grown  before  it 
feeds  to  any  extent  upon  the  other  portions  of  the  square.  It  may 
then  take  the  pistil  and  the  central  portion  of  the  ovary, scooping  out 
a  smoothly  rounded  cavity  for  the  accommodation  of  its  rapidly 
increasing  bulk  (PL  I,  fig.  7;  PI.  Ill,  fig.  15;  PI.  IV,  fig.  24).  So 
rapidly  does  the  larva  feed  and  grow  that  in  rather  less  than  a  week 
it  has  devoured  two  or  three  times  the  bulk  of  its  own  body  when  fully 
grown.  It  sometimes  happens  that  the  square  is  large  when  the  egg 
is  deposited  therein,  and  the  bloom  begins  to  open  before  the  injury 
by  the  larva  is  sufficient  to  arrest  its  development.  In  many  cases  of 
this  kind  the  larva  works  its  way  up  into  the  corolla  and  falls  with  it, 
leaving  the  young  boll  quite  untouched  (PL  V,  fig.  27).  Occasionally 
the  flower  opens  and  fertilization  is  accomplished  before  an}-  injury 
is  done  the  pistil,  and  in  rare  cases  a  perfect  boll  results  from  a  truly 
infested  square.  Sometimes  the  larva  when  small  works  its  way  down 
into  the  ovary  before  the  bloom  falls,  and  in  such  cases  the  boll  falls 
as  would  a  square. 

In  large  bolls  the  larva?  feed  principally  upon  seed  and  to  some  extent 
upon  immature  fiber.  A  larva  will  usually  destroy  but  one  lock  in  a 
boll,  though  two  are  sometimes  injured  (PL  V,  tig.  28). 

ADULT. 

Before  escaping  from  the  square  the  adult  empties  its  alimentary 
canal  of  the  white  material  remaining  therein  after  the  transforma- 
tion. The  material  removed  in  making  an  exit  from  the  cell  is  not 
used  as  food,  but  is  cast  aside.  Weevils  are  ready  to  begin  feeding- 
very  soon  after  they  escape  from  the  squares  or  bolls  in  which  the 
previous  stages  have  been  passed.  For  several  days  thereafter  both 
sexes  feed  almost  continuously  and  seem  to  have  no  other  purpose  in 
life.  They  will  take  squares,  bolls,  or  leaves,  but  they  much  prefer 
the  squares,  and  when  squares  are  present  in  the  field  it  is  probable 
that  leaves  are  seldom  touched.  As  has  been  shown,  however,  weevils 
can  live  for  a  long  time  upon  leaves  alone  when  squares  and  bolls  are 


38 


wanting.     Bolls  are   only  slightly  attacked   so  long   as  there  is  an 
abundance  of  clean  squares. 

The  method  of  feeding  is  alike  in  both  sexes.  The  mouth-parts 
are  very  flexibly  attached  at  the  tip  of  the  snout  (fig.  2)  and  are 
capable  of  a  wide  range  of  movement.  The  head  fits  smoothly  into 
the  prothorax  like  the  ball  into  a  socket  joint  and  is  capable  of  a  con- 
siderable angle  of  rotation.  The  proboscis  itself  is  used  as  a  lever  in 
prying  and  helps  to  enlarge  the  puncture  through  the  floral  envelopes 
especially.  Feeding  is  accomplished  by  a  combination  of  movements. 
The  sharply  toothed  mandibles  serve  to  cut  and  tear,  while  the  rota- 
tion of  the  head  gives  the  cutting  parts  an  auger-like  action.  The 
forelegs  especially  take  a  very  firm  hold  upon  the  square  and  help 
to  bring  a  strong  pressure  to  bear  upon  the  proboscis  during  certain 
portions  of  the  excavating  process.  The  outer  layer  of  the  square, 
the  calyx  of  the  flower,  is  naturally  the  toughest  portion  that  they 
have  to  penetrate,  and  only  enough  is  here 
removed  to  admit  the  snout.  After  that  is 
pierced  the  puncture  proceeds  quite  rapidly, 
combinations  of  chiseling,  boring,  and  prying 
movements  being  used.  While  the  material 
removed  from  the  cavity  is  used  for  food,  the 
bulk  of  the  feeding  is  upon  the  tender,  closely 
compacted,  and  highly  nutritious  anthers  or 
pollen  sacs  of  the  square.  When  these  are 
reached  the  cavity  is  enlarged,  and  as  much  is 
eaten  as  the  weevil  can  reach.  The  form  of 
the  entire  puncture  becomes  finally  like  that 
of  a  miniature  flask. 

Only  after  weevils  have  fed  considerably  do 
sexual  differences  in  feeding  habits  begin  to 
appear  (PL  III,  fig.  13),  the  females  puncturing  mainly  the  base  and 
the  males  the  tip  of  the  square. 

Feeding  punctures  are  much  larger  and  deeper  than  are  those  made 
especially  for  the  reception  of  the  eggs  (PI.  I,  fig.  3);  more  material 
is  removed  from  the  inside  of  the  square  or  boll  and  the  opening  to 
the  cavity  is  never  intentionally  closed.  Feeding  punctures  are  most 
frequently  made  through  the  thinner  portion  of  the  corolla  not  covered 
by  the  calyx.  The  exposed  tissue  around  the  cavity  quickly  dries 
and  turns  brown  from  the  starting  of  decay.  As  a  number  of  these 
large  cavities  are  often  formed  in  one  square  (PL  VI,  fig.  29),  the 
injury  becomes  so  great  as  to  cause  the  square  to  flare  immediately, 
often  before  the  weevil  has  ceased  to  feed  upon  it.  Squares  so 
severely  injured  fall  in  a  very  short  time.  The  injury  caused  by  a 
single  feeding  puncture  is  often  overcome  by  the  square  and  its  nor- 
mal course  of  development  is  continued.  When  feeding  punctures 
are  made  in  squares  which  are  nearly  ready  to  bloom,  the  injury  com- 


Fig.  2.— Mexican  cotton  boll 
weevil,  head  showing  ros- 
trum with  antennae  near 
middle  and  mandibles 
at  end— much  enlarged 
(original). 


89 

moiih  produces  ft  distorted  bloom  (PI.  VI,  fig,  30)  and  in  \<-i\  severe 
eases  the  boll  will  drop  soon  after  setting. 

Alter  the  females  begin   t<>  oviposit   their  feeding  habits   become 
quite  different  from  those  of  the  males.     Up  t«>  iliis  time  i»<>tli  s.-\.n 
move  I  >ii  i  little,  makings  number  of  punctures  In  ;i  single  square;  but 
from  this  point  we  must  consider  the  feeding  habits  of  the  sexes  sep 
arately. 

\l  U.K. 

Studies  of  the  feeding  habits  of  males  have  been  made  both  in  the 
laboratory  and  <>ut  of  doors.  In  the  laboratory  65  males  were  under 
observation  during  a  total  period  of  2,492  weevil-days. a  During  this 
period  2,185  squares  were  supplied  them  and  they  made  5,617  feeding 
punet  ures  in  l  ,582  of  these  squares.  A  Little  calculat  ion  shows  that  they 
averaged  to  make  &j  feeding  punctures  In  each  square,  at  the  rate  of  2j 
punctures  a  weevil  each  day.  These  observations  were  in  most  cases 
made  during  the  latter  part  of  each  weevil's  life.  During  the  first  few 
days  1  hey  have  often  been  found  to  make  from  6  to  9  punctures  a  day. 
A  general  average  of  3  feeding  punctures  a  day  in  the  laboratory 
would  seem  to  be  near  the  actual  figures  during  the  warm  weather. 

As  each  male  while  under  observation  attacked  only  about  -2 
squares  every  3  days,  the  destruetiveness  of  males  seems  compara- 
tively slight. 

Five  males  were  followed  upon  plants  under  a  field  cage  for  a  total 
period  of  145  weevil-days.  During  this  period  they  attacked  08 
squares,  making  therein  a  total  of  177  feeding  punctures.  This 
means  an  average  of  2A>  punctures  per  square  and  an  average  of  1.2 
punctures  per  male  per  day,  making  the  number  of  squares  attacked 
by  each  male  less  than  1  ever}'  2  days.  These  outdoor  observations 
indicate  that  the  laboratory  results,  small  though  they  appear,  are 
yet  higher  than  the  actual  field  numbers.  Whether  in  or  out  of 
doors,  the  activity  of  feeding  decreases  as  the  male  grows  older. 

.Males  choose  to  puncture  more  often  than  do  females  through  the 
tip  portion  of  the  square  not  covered  by  the  calyx.  The  yellow  or 
orange  colored  excrement  is  abundant,  and  owing  to  the  somewhat 
sedentary  habits  of  the  males  it  accumulates  often  in  quite  large 
masses. 

FEMALE. 

After  they  begin  to  oviposit  females  seem  generally  to  feed  less 
upon  one  square  or  in  one  puncture  than  they  do  previous  to  that 
time.  They  obtain  quite  a  considerable  portion  of  their  food  from 
the  excavations  which  they  make  for  the  deposition  of  their  eggs,  and 
as  they  show  a  strong  inclination  to  oviposit  only  in  clean  or  pre- 
viously uninfested  squares,  their  wandering  in  search  of  Buch  squares 

fl  The  term  "weevil-day"  is  used  for  convenience  to  designate  the  product  of 
the  two  factors:  number  of  weevils  multiplied  by  the  number  of  days. 


40 

keeps  their  punctures  scattered  so  long  as  plenty  of  clean  squares  can 
be  found.  When  clean  squares  become  scarce,  the  normal  inclination 
can  not  be  followed  out,  and  the  number  of  punctures  made  in  one 
square  will  be  greatly  increased.  Most  of  the  special  feeding  punc- 
tures of  females  appear  to  be  made  either  in  the  early  morning  or 
near  sundown,  the  middle  and  warmest  portion  of  the  day  being 
given  mainly  to  egg  deposition.  The  total  amount  of  feeding  done  is 
really  very  large,  as  is  shown  by  a  few  figures. 

MALES   AND   FEMALES   TOGETHER. 

During  the  season  of  1003  a  large  number  of  weevils  was  kept  in 
the  laboratory  for  special  study,  but  as  several  weevils  were  confined 
in  each  cage,  the  work  of  the  sexes  can  not  be  positively  separated. 
A  comparison  of  the  results  can  best  be  made  by  means  of  a  tabular 
arrangement  of  the  figures. 

Table  VIII. — Number  of  punctures  per  weevilper  day. 


Number 
of  males. 

Number 
of  fe- 
males. 

Total. 

Average. 

Characterization  of 
lot. 

Weevil 
days. 

Feeding 
punc- 
tures. 

Egg 
punc- 
tures. 

Feeding 

punc- 
tures per 
weevil 
day. 

Egg 

punc-     Period  of 
tures  per  observa- 
female        tion. 
day.     ! 

Hibernated    weevils 
in  laboratory.  - 

Hibernated  females 
in  field  cage 

55 

54 
4 

27 
5 

4,938 
93 

3,258 

7(i 

2,492 

17,406 

284 

16,487 
263 

5,617 

5,702 
489 

3,565 
435 

3.5+ 
3.0+ 

5.0+ 
3.8- 

2.3- 

2.3+ 
5.3- 

2.4- 

6.2+ 

Days. 
45.3+ 

23.3- 

Weevils  of  first  gen- 
eration in  labora- 
tory   

31 

56.2— 

Females,  first  gener- 

14.0 

Males   only,  labora- 
torv.  summer    of 
1903. 

65 

3S.3+ 

Total.... 

151 

90 

10,851 

40,057 

10,191 

FEEDING    OF   HIBERNATED    AVEEVILS    ON   EARLY   COTTON. 

During  the  period  in  which  hibernated  weevils  were  coming  from 
their  winter  quarters  and  seeking  their  first  food,  frequent  examina- 
tions Avere  made  in  fields  where  the  cotton  was  most  advanced  to  learn 
the  first-food  habits  of  such  weevils.  From  statements  made  by  pre- 
vious investigators  the  writer  is  led  to  believe  that  the  season  of  1903 
at  Victoria  was  abnormal  in  respect  to  the  small  number  of  hiber- 
nated weevils  which  wrere  to  be  found  upon  the  young  cotton  in  the 
field.  The  most  careful  search  failed  to  discover  more  than  a  very 
few  weevils,  whereas  at  the  same  season  in  some  years  hibernated 
weevils  have  been  picked  in  large  numbers  from  the  young  cotton 
growing  in  the  infested  territory. 

Whether  they  be  few  or  many,  however,  makes  no  difference  in 
the  feeding  habits  of  the  hibernated  beetles.  The  stage  of  the  cotton 
determines  largely  the  nature  of  the  food  habits  at  this  time.     Owing 


II 

to  the  extremely  wet  winter  and  the  very  late  —  i » i  i 1 1 ^r  * » r  1903,  little 
coi  i  nn  could  be  planted  until  the  latter  pari  of  March  or  i  he  Aral  pari 
of  April.  In  such  a  season  as  this,  therefore,  cotton  musl  be  nmall 
at  the  time  of  the  emergence  <»f  the  wreevils  from  hibernation,  and 
sometime  musl  elapse  before  the  formation  of  the  flrsl  squares  fur- 
nishes the  weevils  with  t  heir  normal  food  supply.  During  this  inter- 
val the  weevil  gets  mosl  of  its  food  from  the  tender,  rapidly  growing 
terminal  portion  of  the  young  plants,  as  several  observers  have  noted. 
The  central  bud,  young  leaves,  or  the  tender  stems  are  attacked  ami 
upon  these  the  weevils  easily  subsist  until  squares  are  developed,  aftei 
which  they  confine  their  injury  to  them. 

The  earliesl  plants  in  afield  seem  to  attracl  most  of  the  weevils, 
and  where  Beppaa  plants  occur  they  serve  as  excellent  traps  i<>  draw 
the  first  attacks.  Thus,  in  the  spring  of  L895Mr.  E.  A.  Schwarz  found 
the  first  emerged  hibernated  weevils  working  upon  seppa  plants  which 
had  sprung  from  2-year-old  roots.  These  plants  seem  to  starl  earlier 
and  grow  more  vigorously  than  do  those  from  Beed  and  are  therefore 
doubly  tempting  to  the  hungry  weevils. 

In  L896  Mr.  Marlatl  noted  "the  eating  in  the  field  on  volunteer  cot- 
ton is  practically  confined  to  the  young  expanding  leases  at  the  bud 
and  to  the  tender  petioles  or  stems  of  this  portion  of  the  plant." 

In  the  spring  of  1903,  in  one  field  of  comparatively  early  eotton,  2 
(>]•  3  acres  in  extent,  the  writer  found,  between  April  24  and  May  11, 
23  weevils  working  on  the  buds  and  tender  leaves  of  seppa  plants 
before  a  single  weevil  was  found  upon  the  young  planted  eotton  bas- 
ing from  4  to  s  leaves. 

If,  however,  the  cotton  should  be  further  advanced  at  the  time  the 
weevils  appear,  they  would  then  go  at  once  to  the  squares.  Even 
then  they  prefer  to  attack  the  most  advanced  plants,  which  have  a 
number  of  nearly  grown  squares,  rather  than  the  smaller  plants  which 
are  but  just  beginning  to  square.  Seppa  plants,  where  such  exist, 
come  in,  therefore,  for  a  large  part  of  the  firsl  at  tack  of  the  hibernated 
weevils.  This  fact  is  well  shown  by  observations  made  by  .Mr.  A.  \. 
Caudell,  of  the  Division  of  Entomology,  at  Victoria,  at  about  the 
middle  of  June,  L902.  In  an  examination  of  100 seppa  plants  growing 
in  a  planted,  held  he  found  that  fully  half  of  the  squares  upon  those 
plants  were  then  infested.  The  planted  cotton  was  just  beginning  to 
form  squares,  and  was  but  slightly  injured  at  thai  time. 

INCREASE    IX    LEAF    AREA    OF    COTTON. 

The  advisability  of  making  observations  upon  this  point  was  sug- 
gested  by  the  attempts  made  to  poison  hibernated  weevils  by  spraying 
early  eotton  with   an   arsenical   insecticide.      As   the   weevils    fed   so 

"  "  Seppa  *'  is  the  term  used  by  the  Mexican  residents  of  South  Texas  to  differ- 
entiate the  cotton  plants  springing  from  the  roots  of  the  previous  year  from  those 
strictly  "volunteer.'*  springing  from  accidentally  scattered  seeds. 


42 

exclusively  in  the  most  recently  unfolded  growing  portions  at  the  tips 
of  the  stems,  it  was  evident  that  the  rapidity  of  increase  in  the  leaf 
area  would  at  least  indicate  the  frequency  with  which  spraying  would 
have  to  be  repeated  in  order  to  keep  in  a  poisoned  condition  the  very 
limited  portion  upon  which  the  weevils  fed. 

Although  the  observations  were  made  after  midsummer,  the  plants 
used  were  of  the  right  size  to  indicate  the  points  desired.  Two  scries, 
each  including  five  average  plants,  were  selected. 

The  plants  used  in  Series  I  had  8  leaves  at  the  time  of  the  first 
observation.  Those  used  in  Series  II  were  older  and  averaged  about 
30  leaves  each.  The  leaves  borne  upon  the  main  stem  were  classed 
as  primary  and  those  from  side  branches  as  secondary  leaves.  Upon 
the  date  of  each  of  the  5  observations  made,  the  number  of  leaves  in 
each  class  was  ascertained,  an  average  leaf  in  each  class  was  quite 
accurately  measured,  and  the  total  product  of  numbers  and  area  thus 
found  was  considered  as  the  approximate  leaf  area  of  the  plant.  The 
error  has  been  reduced  as  much  as  possible  by  taking  an  average  of 
the  5  plants  in  each  series  as  representing  a  typical  plant,  and  it  is 
with  these  results  that  comparisons  have  been  made. 

Table  IX. — Estimated  increase  in  leaf  area  of  cotton,  averages  of  five  plants. 


Primary  leaves. 


Date  of  examination. 


Average 
number 

{)er 
ant. 


Average 
area, 
plant. 


Series  I: 

August  30 

September  13 
September  25 

October  6 

October  17 

Series  II: 

August  30 

September  13 
September  25 

October  6 

October  17 


1902. 


8.0 


11.0 
13.2 


7.8 
8.4 


9.6 
10.0 


Sq.  in. 
64.0 


Percent- 
age of 

daily  in- 
crease. 


Secondary  leaves. 


Average  Avpra„p 
number   A™^e 

pPant.        P**. 


136.8 
231.6 
309.6 
376.6 

177.2 

8.0 
5.4 
3.0 
2.0 

229.2 
241.6 
214.8 
216.8 

2.6 
.04 
«-1.0 

0.0 

8.0 

16.6 

22.6 

31.0 

21.6 

24.8 
42.4 


Sq. 


41.2 
187.4 
347.X 
522.4 

266.8 
341.4 
514.0 
619.2 
808.8 


Percent- 
age of 

daily  in- 
crease. 


30.0 
7.8 
4.6 


2.0 
3.6 
1.8 
2.1 


«  Decrease  of  1  per  cent  due  to  falling  of  old  primary  leaves. 

Several  facts  are  evident  from  an  examination  of  this  table.  After 
the  plant  has  acquired  about  eight  primary  leaves  the  formation  of 
branches  and  of  secondary  leaves  began,  thereby  multiptying  the 
number  of  growing  points.  From  this  time  on  the  greater  part  of  the 
increase  in  leaf  area  took  place  in  the  secondary  leaves.  By  far 
the  most  rapid  period  of  leaf  growth  occurred  at  about  the  time  when 
squares  first  began  to  form.  In  Series  I  the  average  total  leaf  area 
practicalry  doubled  every  ten  days  through  the  seven  weeks  under 
observation.  In  Series  II  the  plants  were  older  to  start  with,  and  it 
required  about  forty  days  to  double  the  leaf  area. 

Everyone  now  concedes  that  it  is  useless  to  attempt  the  spraying 
of  full-grown  cotton  such  as  is  represented  in  Series  II.     The  extreme 


i:; 

rapidity  of  Increase  In  the  foliage  area  shown  in  the  ftrel  pari  of 
Scries  I  shows  that  spraying  must  i»<i  repeated  everj  week  or  ten  days 
if  even  one-half  of  1 1 1 « *  entire  Leaf  area  is  t<>  be  kept  poisoned.  When 
in  connection  with  the  Large  per  oenl  of  daily  Increase  we  consider 
how  much  of  that  percentage  is  being  unfolded  at  tin-  verj  tip  of  the 
stem;  thai  upon  that  Limited  tip  area  alone  will  the  weevil  feed  before 
the  formation  of  Bqnares;  that  after  the  formation  of  squares  it 
appears  t<>  be  absolutely  impossible  to  poison  the  weevil's  food  sup- 
ply, and  also  that  the  irregular  emergence  of  the  weevils  from  hiber- 
nation may  extend  through  several  weeks,  it  at  once  becomes  evident 
that  Bpraying  early  cotton  for  hibernated  weevils  is  almost  as  imprac- 
ticable as  the  spraying  of  older  cotton  is  now  acknowledged  t<>  l>c 

EFFECTS   OF    FEEDING    UPON    SQUARES    AND    BOLLS. 

Prom  numerous  large,  open,  feeding  punctures  a  square  becomes 

so  severely  injured  that  it  Hares  very  quickly,  often  within  24  hours. 
.Males  usually  make  the  Largest  punctures,  and  always  leave  them  open 
while  they  remain  for  a  day  or  more  working  upon  the  same  square. 
It  lias  been  often  found  that  squares  thus  injured  by  a  male  will  Hare 
before  the  weevil  leaves  it.  The  time  of  flaring  depends  upon  the 
degree  of  injury  relative  to  the  size  of  the  square.  Thus,  small  squares 
receiving  only  a  single  large  feeding  puncture  in  the  evening  are  found 
widely  flared  in  the  morning.  On  the  other  hand,  large  squares  which 
are  within  a  few  days  of  the  time  of  their  blooming  may  receive  a 
number  of  punctures  without  showing  any  noticeable  flaring.  Fre- 
quently a  square  which  has  flared  widely  will  be  found  later  to  have 
closed  again  and  to  have  formed  a  distorted  bloom  (PI.  VI,  fig.  30;  PI. 
VII,  fig.  31),  and  occasionally  such  squares  develop  into  normal  bolls. 
In  squares  of  medium  size  a  single  feeding  puncture  does  not  usually 
destroy  the  square.  The  destruction  of  a  square  by  feeding  results 
either  from  drying,  decay,  or  a  softened,  pulpy  condition  of  the 
interior  which  is  the  consequence  of  the  weevil  injury. 

Bolls  are  quite  largely  fed  upon  after  infestation  has  reached  its 
height.  Small  and  tender  bolls  are  often  thoroughly  riddled  by  the 
numerous  punctures  (PL  VII,  fig.  32).  Small  bolls  so  severely  injured 
fall  within  a  short  time.  Larger  bolls  may  receive  more  punctures 
without  being  so  severely  injured.  A  comparison  of  the  external 
and  internal  effects  in  such  cases  is  shown  in  PI.  VIII,  figs.  34,  35. 
Abnormal  woody  growth  takes  the  place  of  the  normal  development 
of  the  fiber,  and  a  softening  and  decay  of  the  seeds  often  accompanies 
this  change.  One  or  more  locks  may  be  destroyed  while  the  remain- 
der of  the  boll  develops  in  perfect  condition  (PI.  VII,  fig.  33;  PI.  X, 
fig.  38). 

After  the  bolls  become  about  half  grown  the  effects  of  feeding  are  less 
liable  to  cause  the  boll  to  fall  (PI.  I,  fig.  10).  The  puncture  becomes 
closed  by  a  free  exudation  of  the  sap  and  a  subsequent  woody  growth, 


44 

which  forms  frequently  an  excrescence  the  size  of  half  a  pea  upon  the 
inner  side  of  the  carpel.  An  excrescence  of  this  character  usually 
results  from  an  egg  puncture,  and  often  from  feeding  punctures. 

DESTRUCTIVE    POWER    BY   FEEDING. 

A  glance  at  the  figures  in  Table  VIII  (p.  40)  is  sufficient  to  show 
the  great  destructive  power  of  the  Mexican  cotton  boll  weevil.  It 
may  be  seen  that  both  in  the  field  and  in  the  laboratory  the  weevils 
of  the  first  generation  are  more  active  in  making  punctures  than  are 
the  hibernated  Aveevils.  These  generations  overlap  too  far  to  attribute 
this  difference  to  the  influence  of  a  higher  temperature  alone,  though 
this  factor  will  account  for  a  large  part  of  it.  A  comparison  of  the 
figures  for  males  alone  with  those  for  females  alone  or  with  those  for 
males  and  females  together  shows  that  it  is  very  conservative  to  say 
that  males  make  less  than  half  as  many  punctures  as  do  females.  By 
the  habit  of  distributing  their  punctures  among  a  greater  number  of 
squares  the  destructiveness  of  the  females  becomes  at  least  five  times 
as  great  as  that  of  the  males. 

This  great  capacity  for  destruction  has  been  one  of  the  most  evident 
points  in  the  history  of  the  spread  of  the  weevil,  and  deeply  impressed 
the  entomologists  who  first  studied  the  insect  in  Texas.  In  1895  Mr. 
E.  A.  Schwarz,  in  writing  of  the  work  of  the  weevil  at  Beeville,  said : 

Each  individual  specimen  possesses  an  enormous  destructive  power  and  is  able 
to  destroy  hundreds  of  squares,  most  of  them  by  simply  sticking  its  beak  into 
them  for  feeding  purposes. 

SUSCEPTIBILITY   OF   VARIOUS   COTTONS. 

An  excellent  opportunity  for  observations  upon  this  point  was 
obtained  upon  the  laboratory  grounds  at  Victoria  by  growing  within 
a  small  area  plants  of  several  varieties  of  American  Upland,  Sea 
Island,  Egyptian  (Mit  Afifi),  Peruvian,  and  Cuban  cotton  (Algodon 
sylvestre).  The  Peruvian  cotton  made  a  remarkably  large  growth, 
but  put  out  no  squares,  so  that  it  does  not  really  enter  into  this  com- 
parison. The  Mit  Afifi  seed  was  obtained  through  the  courtesy  of  the 
Bureau  of  Plant  Industry  of  this  Department  from  a  field  grown  the 
preceding  season  at  San  Antonio,  Tex.,  in  which  circumstances  led 
some  observers  to  the  opinion  that  the  variety  was,  to  a  certain  extent, 
immune.  The  observations  at  the  laboratory  were  made  by  carefully 
examining  the  plants,  looking  into  each  square,  and  removing  every 
weevil  and  infested  square  found.  If  there  were  any  distasteful  or 
resistant  cotton  among  these,  it  would  surely  be  found  in  this  way; 
and  if  any  variety  were  especially  attractive  to  the  weevils  it  would 
be  equally  apparent.  Infested  squares  being  removed,  the  accident 
of  association  or  proximity  would  not  determine  the  location  of  the 
weevils  found,  but  all  might  be  considered  as  having  come  to  the  cot- 
ton with  equal  opportunities  to  make  their  choice  of  food,  and  accord- 


i:. 


i  1114,1  \  their  location  has  been  considered  as  indicating  such  choice. 
The  period  <>f  observation  extends  from  June  to  November,  <\<-<'|»i 

w  ii h  tlir  c  uhan  coiion,  which  was  planted  late  and  began  to  square 
during  the  latter  part  of  August.  For  the  purpose  of  this  comparison, 
both  the  varieties  and  the  several  plots  of  the  American  cotton  will  be 
considered  together,  as  no  evidence  of  preference  was  found  among 
them. 

In  making  a  comparison  of  the  results  three  elements  must  be  oon- 
sidered  for  each  variety  of  cotton :  First ,  the  number  of  plan  is  of  cadi 
variety  ;  second,  the  number  of  days  during  which  each  kind  was 
under  observation;  third,  the  total  number  of  weevils  found  on  each 
class  of  cotton.  'The  elements  of  numbers  of  plants  and  times  of 
observation  may  be  expressed  by  the  product  of  those  two  factors 
forming  a  term  which  we  may  call  " plant-days."  The  total  number 
of  weevils  found  upon  any  class  of  cotton  divided  by  the  number  of 
"plant-days"  will  give  the  average  number  of  weevils  attracted  by 
each  plant  for  each  day,  and  these  numbers  furnish  a  means  of  direct 
comparison  and  show  at  a  glance  the  average  relative  attractiveness 
of  each  class  of  cotton.  The  following  table  presents  these  results  in 
comparable  form: 

Table  X. — Relative  attractiveness  of  various  cottons. 


Number 

of 
plants. 

Total. 

Average. 

Class  of  cotton. 

Plant 
days. 

Weevils   Infested 
found,     squares. 

Weevils 
per  plant 
per  day. 

Infested 
squares 

per 
weevil. 

Relative 
attract- 
iveness. 

62 

4,920 

287 

3,507 

0.058  + 

12.2+ 

1.0 

5 

8 
8 

120 
552 

808 

11 
64 

207 

136 
1,089 
2,013 

.092 

.116- 

.256+ 

12.  \ 
17.0+ 
9.7+ 

1.6  [• 

2.0 

Egyptian 

4.4  + 

Total  of  3  non- Amer- 
ican cottons 

21 

1,480 

282 

3,238 

.191- 

11.5- 

3. 3- 

An  examination  of  these  figures  shows  that  American  Upland  cotton 
is  less  subject  to  the  attacks  of  the  weevil  than  any  of  the  others,  and 
that  Egyptian  (Mit  Afifi)  is  by  far  the  most  susceptible.  The  differ- 
ence in  degree  is  most  plainly  shown  in  the  column  of  "relative 
attractiveness."  It  would  certainly  seem  difficult  to  formulate  a 
stronger  argument  for  the  cultivation  of  American  cottons  alone  within 
the  weevil-infested  district  than  is  presented  by  these  figures.  The 
weevils  gathered  so  thickly  upon  the  Egyptian  cotton  that  the  plants 
could  not  produce  sufficient  squares  to  keep  ahead  of  the  injury,  and 
therefore  the  average  number  of  infested  squares  for  each  weevil  is 
only  three-fourths  as  great  with  that  variety  as  with  less  infested 
kinds,  but  the  average  injury  to  each  square  was  greater  than  with 
any  other. 

The  practical  appli3ation  of  these  observations  may  be  emphasized 


46 

still  further  by  the  statement  that  in  spite  of  the  frequent  and  care- 
ful removal  of  weevils  from  these  cottons  during  the  entire  season 
none  of  the  non- American  varieties  made  a  single  boll  of  good  cotton, 
so  great  was  the  actual  weevil  injury  to  them,  while  American  cotton 
with  the  same  treatment  developed  a  large  number  of  bolls. 

The  results  are  still  further  sustained  by  observations  upon  larger 
areas  of  American  and  Egyptian  cotton  under  field  conditions  in  three 
localities  in  Texas,  no  weevils  being  removed  from  either  kind.  At 
Victoria,  Tex.,  on  August  26,  1903,  an  examination  showed  that  96 
per  cent  of  Egyptian  squares  were  infested,  while  an  average  of  13 
fields  of  American  showed  75.5  per  cent.  At  Calvert,  Tex.,  on  Sep- 
tember 4,  Egyptian  showed  100  per  cent  infested,  while  the  American 
varieties  growing  alongside  showed  91  per  cent.  Similar  results  were 
found  at  San  Antonio.  Though  growing  in  close  proximity,  the  Egyp- 
tian produced  no  staple  whatever,  while  the  American  gave  better 
than  an  average  yield  in  spite  of  the  depredations  of  the  weevil. 

In  accordance  with  these  observations,  it  appears  that  in  developing 
a  variety  of  cotton  which  shall  be  less  susceptible  to  weevil  attack  by 
far  the  most  promising  field  for  work  lies  among  the  American  varie- 
ties, and  of  these  the  very  early  maturing  kinds  are  most  promising. 

The  question  of  choice  of  different  varieties  for  food  was  tested  in 
the  laboratory  by  Dr.  A.  W.  Morrill,  by  placing  squares  of  two  kinds  of 
cotton,  American  and  Egyptian,  in  alternate  rows  in  a  breeding  cage 
(PL  XII,  fig.  48),  so  lettered  and  numbered  that  each  square  could 
be  exactly  located.  Weevils  were  then  placed  so  £hat  they  could 
take  their  choice  of  these  squares,  and  observations  from  8  a.  m.  to  6 
p.  m.  were  made  upon  the  location  and  activity  of  the  weevils. 
Though  this  experiment  was  repeated  four  times,  no  positive  evidence 
was  obtained  to  show  that  weevils  had  any  choice  as  to  which  kind  of 
squares  they  fed  upon.     Table  XI  presents  a  summary  of  these  results. 

Table  XI. — Breeding-cage  observations  upon  weevil  choice  of  American  and 

Egyptian  squares. 


Period  of 
observa- 
tion. 

Num- 
ber of 
obser- 
va- 
tions. 

American  squares. 

Egyptian  squares. 

Ex- 
peri- 
ment. 

Weevils 
used. 

Total 
num- 
ber. 

In- 
fested. 

Feed- 
ing 
punc- 
tures. 

Egg 
punc- 
tures. 

Total 
num- 
ber. 

In- 
fested. 

Feed- 
ing 
punc- 
tures. 

Egg 
punc- 
tures. 

1 

2 

3 

4 
5 

12  m.  to  8 
a.  m 

11.45a.m. 
to    9.45 
a.  m 

12  m.  to  5 
p.m. day 
after . . . 

11.45  a.  m. 
to  9  a.m 

6  p.  m.  to 
8  a.m... 

Total. 

8 

5 

5 
5 

1 

10 

10 

10 
10 

18 

16 

16 

16 

16 

4 

12 

5 

7 
6 
2 

15 

19 

25 
17 

7 

5 

1 

2 
6 
0 

16 

16 

16 

16 

4 

5 

5 

9 
8 
2 

12 

13 

27 
14 
10 

3 

3 

2 
3 
0 

24 

58 

68 

32 

83 

14 

68 

29 

76 

u 

Iii  experiments  I  and  2  the  American  squares  were  attacked  more 
extensivel}  than  were  the  Egyptian,  while  in  experiments  3  and  5 
greater  injury  was  done  to  the  Egyptian,  [n  experiment  I  the  smaller 
number  of  egg  and  feeding  puncl  ares  made  in  i  he  Egypt  ian  squares  is 
counterbalanced  by  I  he  larger  Dumber  of  squares  attacked.  Although 
the  totals  from  these  Ave  tests  show  stightly  Less  injury  to  the  Egyp- 
tian than  to  the  American  squares,  it  could  hardly  be  expected  that 
two  arbitrarily  chosen  series,  even  if  of  the  same  variety,  would  show 
any  closer  agreement  in  the  points  of  comparison  made  in  this  table 

than  is  therein  shown  by  the  American  and  Egyptian  squares. 

HAS   THE    WEEVIL    ANY    oTIIKK    FOOD    PLANT  THAN    COTTON? 

The  question  of  the  possibility  of  boll  weevils  feeding  upon  some 
other  plant  than  cotton  is  one  of  groat  importance.  It  is  a  well- 
known  fact  that  insects  which  have  few  food  plants  usually  con  line 
their  attacks  to  closely  related  plants  belonging  to  the  same  botanical 
family,  or  even  genus.  Accordingly,  most  of  the  plants  which  have 
been  tested  especially  are  most  closely  related  to  cotton.  Four  species 
of  Hibiscus  (If.  escult  ntus,  H.  vesicarius,  H.  manihot,  H.  moscheutos) 
were  grown  and  an  effort  made  to  see  whether  weevils  would  feed 
upon  either  the  leaves,  buds,  or  seed  pods.  In  no  case,  however,  did 
they  live  on  any  of  these  for  any  considerable  time,  though  they  fed 
slightly  upon  some  of  the  parts.  Hibernated  weevils  starved  in  an 
average  time  of  about  4  dajTs  with  leaves  of  either  okra  or  Sunset 
Hibiscus.  The  buds  and  seed  pods  were  not  formed  at  that  time,  so 
could  not  be  tested.  Weevils  of  the  first  generation,  which  had  had 
no  cotton  for  food,  were  placed  upon  Sunset  Hibiscus,  and  these 
starved  in  an  average  of  3  or  4  days.  First  generation  weevils,  which 
had  fed  for  a  few  days  on  squares,  were  placed  upon  leaves,  buds, 
and  seed  pods  of  Hibiscus  vesicarius.  Though  the}'  fed  a  little,  all 
starved  in  an  average  of  about  5  days.  A  lot  of  first  generation 
weevils,  fed  first  for  several  days  with  squares,  were  given  leaves, 
buds,  and  seed  pods  of  okra.  More  feeding  was  done  by  this  lot  than 
by  any  other,  all  parts  being  slightly  attacked.  These  weevils  lived 
for  an  average  of  7  days. 

Numerous  other  plants,  including  sunflower  (Hdianthus  annuus), 
bindweed  (Convolvulus  repens),  the  slender  pigweed  and  the  spiny 
pigweed  (Amardnthus  hybridus  and  A.  spinosus),  and  western  rag- 
weed ( [u  1  nibrosia  psilostachya),  and  various  other  species  of  weeds  and 
glasses  which  occur  more  or  less  frequently  around  cotton  fields 
were  tested,  but  in  no  case  was  feeding  noticed  except  in  the  case  of 
weevils  supplied  with  pieces  of  the  stem  of  sorghum,  the  stems  of  which 
were  cut  into  short  lengths  and  some  of  the  pieces  split  lengthwise. 
Upon  the  exposed,  juicy  pith  weevils  fed  considerably,  but  they  did 
not  puncture  through  the  hard  stem  to  obtain  the  juice.     The  sweet 


48 

sap  found  in  the  pith  sustained  weevils  for  some  time  in  the  labora- 
tory, bu1  where  obliged  to  puncture  the  stem,  as  they  would  be  in  the 
field,  they  would  never  attack  sorghum,  except  possibly  freshly  cut 
stubble.  Among  the  many  plants  tried,  therefore,  none  has  beeu 
tound  to  show  any  capacity  for  sustaining  the  lives  of  weevils  in  the 
field  in  the  absence  of  cotton. 

The  question  of  the  original  food  plant  of  the  weevil  has  received 
considerable  attention  from  this  Division,  the  investigations  made  in 
Cuba  being  pari  icularly  thoroughand  conclusive.  In  that  island  some 
varieties  of  cotton  grow  wild  and  are  perennial.  After  most  careful 
search  Mr.  E.  A.  Schwarz  wrote  in  the  spring  of  1903:  "There  is  not 
the  slightest  doubt,  in  my  opinion,  that  the  original  and  only  food 
plants  of  the  weevil  are  the  varieties  of  Gossypium  and  here  in  Cuba 
the  variety  known  as  kidney  cotton."  The  investigations  of  the 
Division  of  Entomology  have  given  special  attention  to  the  possibility 
of  the  boll  weevil  breeding  on  other  plants  than  cotton.  Throughout 
the  investigations  of  Prof.  C.  H.  T.  Townsend  in  southern  Texas  and 
in  Mexico  and  the  careful  studies  made  by  Mr.  Schwarz  in  Texas  and 
in  Cuba  and  the  observations  made  by  the  writers  in  Texas  every 
plant  closely  related  to  cotton  has  been  most  carefully  watched,  and 
the  uniform  failure  to  find  the  weevil  upon  any  other  plant  makes  it 
practically  certain  that  cotton  is  its  only  food. 

INSECTS  OFTEN  MISTAKEN  FOR  THE  BOLL  WEEVIL. 

Man}'  species  of  insects  have  been  mistaken  for  the  Mexican  cotton 
boll  weevil.  Among  them  the  two  most  commonly  reported  in  Texas 
have  been  an  acorn  weevil  (PL  XIV,  fig.  55)  and  a  species  commonly 
found  upon  bloodweed  or  ragweed.  The  chief  reason  for  the  promi- 
nence of  these  two  species  is  not  that  the}'  resemble  the  boll  weevil 
more  closely  than  do  others,  but  rather  that  their  habits  bring  them 
into  closer  proximity  with  cotton  fields  and  their  abundance  has  led  to 
their  more  frequent  discovery.  The  acorn  weevil  has  in  a  number  of 
cases  been  taken  in  lantern  traps  set  in  cotton  fields,  and  the  mistake 
in  the  proper  identification  of  the  species  has  given  currency  to  the 
report  that  the  boll  weevils  are  attracted  to  lights,  which,  however,  is 
never  the  case.  There  is  no  authentic  record  of  a  single  boll  weevil 
having  been  caught  at  any  light.  Only  very  rarely  and  under  excep- 
tional conditions  will  the  acorn  weevil  feed  at  all  upon  cotton  bolls. 

Though  the  bloodweed  weevil  (PL  XIV,  fig.  5-4)  has  been  taken 
from  cotton  plants,  no  evidence  has  been  submitted  showing  that  it 
was  actually  feeding  thereon,  and  it  is  more  likely  that  such  specimens 
had  merely  strayed  to  the  cotton  from  bloodweed  growing  near. 

Another  species  of  weevil,  Desmoids  scapalis  (PL  XIV,  fig.  58),  is 
much  less  common  and  therefore  less  frequently  mistaken,  but  resem- 
bles the  boll  weevil  in  general  appearance  far  more  closely  than  does 


Fig.  29.— Squares  Much  Fed  Upon.  Natural  Size.    'Original. 


Fig.  30. 


-Distorted  Bloom,  Caused  by  Feeding  Upon  Large  Square.  Natural 
Size.    "Original,  i 


• 


VII. 


Feeding  Injuries  on  Blooms  and  Bolls. 

Fig.  31,  Blooms  distorted  by  feeding  punctures,  open  but  imperfect,  two-thirds  natural  >ize:  fig. 
32,  small  boll  riddled  by  feeding  punctures,  natural  size;  rig-.  33,  one  lock  of  boll  destroyed  by 
feeling  punctures,  two-thirds  natural  -ize.     (Original.) 


!«• 

either  of  the  Bpeoies  previously  mentioned.  This  ins<-<-i  haa  been 
found  attacking  white  prickly  poppy  (Argemoru  alba)  and  tumble- 
weed  ( .1  iinifti nflius  tjiui  cizans)  in  the  spring,  and  probably  breeds  on 
Prionopsis  ctliata  Nfutl  and  tin-  broad-leaved  gum  plant  (Orindelia 
sqtuirrosa). 

In  general  the  food  habits  <>f  any  species  are  among  its  distinctive, 
specific  characters,  and  as  the  structural  differences  arc  easily  over- 
Looked  and  difficult  of  appreciation  by  anyone  unacquainted  with  ih<- 
careful  study  of  insects,  a  rather  full,  though  by  no  means  complete, 
lis!  is  here  given  of  the  species  which  have  been  reported  i<>  the 
Division  of  Entomology  as  having  been  confused  with  the  1><>11  weevil." 
Many  of  the  most  common  species  will  be  found  figured  among  the 
illustrations.  The  scientific  names  of  the  insects  are  given  because 
they  are  definite  and  refer  positively  to  a  single  species,  whereas  the 
common  names  are  used  so  loosely  that  the  same  name  may  be  applied 
to  a  number  of  species  having  possibly  similar  habits.  The  boll  wee^  ii 
is  included  in  this  list,  and  figures  of  the  adult  are  given  in  the  plates 
to  facilitate  comparison.  In  many  cases  no  common  name  lias  yet 
been  given  to  the  species.  Seven  of  the  species  mentioned  attack 
living  cotton  and  five  species  are  found  feeding  only  in  decaying  bolls. 
The  occurrence  of  the  remainder  upon  cotton  is  merely  incidental. 

Insects  often  mistaken  for  the  boll  weevil. 


Scientific  name. 


Common  name. 


Plum  gouger 
Acorn  weevil 


Anthonomus  grandis  Boh Mexican  cotton  boll  weevil 

Anthonomus  albopilo&usDietz. 

Authonomus  prunicida 

Bala  n  in  US  u  n  if  arm  is  auct 

(  «  ntrinuspeniceUus  Hbst 

(  <  a  triii  us  picumnus  Hbst 

Chalcoderm  us  omens  Boh Cowpea-pod  weevil 

Desmoris  sea  pa  I  is  Lee ! 

Desmoria  const  rictus  Say 
Dorytomus  mucidus'Lec. 

I.ixus  Icesicollis  Lee 

Coccotorus  scutellaris  ... 

Ba  ris  stria  ta  Say 

Boris  transversa  Say Transverse  Baris.. 

Anthribus  cornutus  Say Horned  stem  borer 


Usual  food  plant. 


Cotton  squares  and  bolls. 


Blood- weed  weevil 

Apple  curculio 

Striped  Baris 


Araecerus  faaciculatus  DeG 


Coffee-bean  weevil 


Imbricated  snout  beetle 


Mexican  rose  beetle. 


Epicarus  inibricatus  Say... 

Hylobius  juries  Hbst 

Khynchites  mexicanus  Gyll 

Tych ius  sordidus Lee 

( tph  ryastes  b  ituberosus  Shp  . . .  I 

Trichobaris  mucorea  Lee ,  Tobacco-stalk  weevil. 

«In  the  preparation  of  this  list  we  are  under  obligations  for  assistance  to  Mr. 
F.  H.  Chittenden,  who  has  also  furnished  information  in  regard  to  the  food  habits 
of  the  species. 

21739— No.  45—04 4 


Plums...  ..  XIV,57. 

XIY,55. 
XY,  61. 


Acorns 

Beetle  in  flowers 

do 

Cowpeapods XV.  63,6 

Broad-leaved  gum  plant .  XIV, 


Plato 
figure. 


XIV,  52,53. 


Willow. 

Ragweed  (Ambrosia  spp).  XIV,  54. 

Apple XIV.  56. 

Stems  of  ragweed 

Roots  of  cocklebur X  V.  59,  < 

Cotton  stems 

Coffee  beans  and  old  cot-     XV.  62. 

ton  bolls. 
Omnivorous XVI,  69. 


Beetles  attack  rose 

Common  in  cotton  fields. 

Found  on  cotton 

Tobacco  stalks 


50 


Insects  often  mistaken  for  the  l><>/l  weevil — Continued. 


Scientific  name. 

Common  name. 

Usual  food  plant. 

Plate 
figure. 

OTHER    BE]   PLIS8 

Monocrepidius  vespertinus  Fab 

Larva  in  grass  roots 

XVI.  Til. 

Notoxus  monodon  Fab... 

Cotton-stalk  borer 

Larva  in  ground 

Ataxia  crypto  Say 

Cotton  stalks 

XVI,  68. 

0libru8  apicalis  Mela 

Decaying  bolls 

Carpophilus  hemipterus  Linn  _. 

Develops  in  decaying  bolls 

Carpopkilus  dimidiatus  Fab... 

do 

Epuixea  cestiva  Linn 

--do.. 

( 'atliartiis  gemellatus Dnv 

Grain  beetle 

do 

Tribolium  ferrugineum  Fab 

Flour  beetle 

Attacks  seed 

BUGS  AND  OTHER   INSECTS. 

Homalodisca  triguetra  Fab 

Sharpshooter 

XVI,  66, 66. 

Oticometopia  undata  Fab 

"Waved  sharpshooter 

do 

Dysdercus  suturellus  H-Sch 

Cotton  stainer 

Cotton  bolls 

XVI  Si 

IS   COTTON-SEED   MEAL   ATTRACTIVE? 


LABORATORY    OBSERVATIONS. 


On  account  of  the  popular  impression  that  cotton-seed  meal  will 
attract  weevils  it  has  been  necessary  to  conduct  a  rather  full  series  of 
experiments.  To  ascertain  the  possibility  of  using  this  substance  as 
an  attractaut  for  the  weevil  in  field  work  three  series  of  laboratory 
tests  were  first  made.  The  weevils  used  were  obtained  from  the  same 
source  in  all  tests.  The  first  series  was  designed  to  test  the  ability  of 
the  weevils  to  live  upon  cotton-seed  meal  alone  as  a  food.  The  sec- 
ond series  was  intended  to  show  whether  the  weevils  would  prefer  the 
meal  to  cotton  leaves  as  an  indication  of  the  possibility  of  attracting 
hibernated  weevils  before  the  formation  of  squares  in  the  spring. 
The  third  series  was  planned  to  show  whether  the  weevils  would  pre- 
fer the  meal  as  a  food  when  squares  could  be  easily  found.  The 
cotton -seed  meal  used  was  obtained  fresh  from  the  oil  mill  and  the 
experiments  started  during  the  latter  part  of  November. 

Weevils  fed  rather  sparingly  upon  the  meal  in  Series  I.  It  did  not 
seem  to  agree  with  them  as  a  food  and  they  showed  no  special  inclina- 
tion to  feed  upon  it.  Twenty-three  of  the  24  weevils  confined  upon 
meal  alone  died  in  from  2  to  13  days,  showing  an  average  length  of 
life  of  slightly  over  6  days.  These  weevils  either  starved  to  death 
rather  than  eat  the  cotton-seed  meal  or  else  they  were  not  able  to  eat 
;i .  The  drjr  and  empty  bodies  of  all  dead  weevils  showed  that  death 
was  caused  by  starvation  and  not  by  disease.  Being  entirely  covered 
with  the  fine  meal  did  not  seem  to  have  any  bad  effect  upon  them. 
As  weevils  without  food  or  water  showed  an  average  length  of  life 
slightly  over  0  days,  agreeing  exactly  with  the  period  in  this  test,  it 
appears  that  cotton-seed  meal  is  not  only  not  a  food  for  the  weevil, 
but  also  that  it  is  not  capable  of  x>rolonging  their  lwes  to  any  appre- 
ciable extent. 


51 

In  Scries  11  l'I  weevils  were  confined  with  fresh  ootton  Leaves  and 
cotton-seed  meal  as  food.  During  the  297  "weevil-days"  that  this 
ezperimenl  was  eon  tinned  but  one  weevil  died.  The  average  period 
of  the  test  for  each  weevil  was  ii  days.  The  weevils  fed  almost 
wholly  upon  Leaves.  Occasionally  one  would  feed  a  Little  on  the 
meal,  hut  they  certainly  preferred  the  Leaves,  and  the  result*  show 
that  Leaves  alone  were  responsible  for  the  Longer  Life  of  these  \\<<-\  Us. 
The  20  survivors  were  placed  in  hibernation  December  _<».  L902,  but 
all  died  before  April  L5,  L903. 

In  Series  III  freshly  picked  squares  were  placed  with  the  meal  to 
see  winch  would  attract  the  weevils.  Fresh  meal,  as  well  ;^  squares, 
was  supplied  at  frequent  intervals.  During  the  L58  "  weevil-days " 
that  thistest  continued  not  one  of  the  10  weevils  died.  The  average 
period  of  the  test  was  almost  10  days,  and  after  it  the  weevils  were 
placed  in  hibernation,  but  all  died  before  April  L5,  1903.  In  only  one 
instance  was  a  weevil  observed  feeding  upon  the  meal.  From  this 
test  it  was  evident  that  eotton-seed  meal  has  not  the  power  to  attract 
weevils  from  squares,  even  when  the  latter  have  been  picked  for 
several  days. 

In  spite  of  the  complete  failure  indicated  by  these  results,  a  series 
of  field  tests  was  made  during  the  late  fall  of  1902. 

FIELD   TESTS. 

In  order  to  settle  this  question  finally,  two  series  of  field  tests  were 
made,  one  during  the  fall,  when  weevils  were  abundant  but  full-fed 
and  cotton  still  standing,  and  the  other  during  the  envly  spring,  with 
the  view  of  attracting  weevils  as  they  came  from  hibernation  before 
cotton  began  to  square. 

Fall  of  1902. — Cotton-seed  meal  fresh  from  the  mill  was  placed  in 
10  cheese-cloth  bags,  which  were  shaken  so  that  the  fine  dust  from  the 
meal  covered  the  outside  of  each  bag.  The  bags  were  numbered  and 
then  tied  to  cotton  plants  in  infested  fields  at  about  the  middle  of  the 
plants.  The  bags  were  so  distributed  as  to  test  fields  in  which  the 
following  conditions  prevailed:  One  field  entirely  black  from  frost, 
one  nearly  black,  one  about  half  green,  and  one  still  entirely  green. 
The  number  of  weevils  on  the  plant  to  which  the  bag  was  attached 
was  noted  each  day  to  ascertain  in  a  general  way  the  number  of  wee- 
vils which  would  be  very  near  the  meal  and  able  to  reach  it  in  the 
ordinary  course  of  travel  over  the  plant  without  having  to  fly  to  it. 
Weevils  on  adjacent  plants  would  naturally  come  within  the  sphere 
of  influence  if  such  existed,  but  they  were  disregarded.  After  the 
failure  of  the  meal  to  attract  weevils  in  the  field  became  apparent, 
weevils  were  caught  and  placed  upon  the  bags  to  see  if  they  would 
stay  there. 

Altogether  65  observations  were  made,  covering  a  period  from  Novem- 
ber 24  to  December  16.     The  weather  was  generally  cool,  averaging 


52 

about  61°  F.,  mean  temperature,  and  cotton  had  ceased  to  grow. 
Counting  each  weevil  found  at  each  observation,  only  5  were  found 
upon  the  10  bags  of  meal.  Of  these  5,  3  were  hidden  in  the  folds  of 
the  cloth  for  shelter  and  were  not  feeding.  One  weevil  was  counted 
twice  and  was  the  only  one  found  that  appeared  to  be  feeding  upon  the 
meal.  During  this  period  a  total  of  163  weevils  was  found  upon  the 
top  parts  of  the  plants  to  which  the  bags  were  attached.  This  is  con- 
siderably below  the  real  number  present,  because  in  many  instances 
this  examination  was  not  made,  and  doubtless  weevils  were  overlooked 
even  when  examination  Avas  made. 

At  various  times  27  weevils  were  placed  directly  upon  the  bags  of 
meal  and  given  every  opportunity  to  show  whether  they  would  stay 
thereon  if  they  accidentally  found  the  meal.  Only  one  of  this  num- 
ber stayed  upon  the  bag  for  24  hours,  and  this  one  remained  in  the 
shelter  of  the  cloth. 

The  unattractiveness  of  cotton-seed  meal  for  the  weevils  seems 
absolutely  proven  so  far  as  fall  conditions  are  concerned. 

Sjiring  of  1903. — These  tests  were  intended  to  show  whether  hiber- 
nated weevils  would  be  attracted  to  the  meal  before  squares  were  to 
be  found  in  the  field.  Two  series  of  experiments  were  planned,  using 
four  bags  of  meal  in  each.  For  the  location  of  the  first  series  a  field 
was  chosen  which  was  known  to  have  been  badly  infested  with  wee- 
vils up  to  December  18,  1902.  This  field  was  not  replanted  with  cot- 
ton in  1903,  nor  was  there  another  field  in  the  vicinity,  so  that  weevils 
coming  from  hibernation  would  find  no  possible  food  except  the  meal. 
A  number  of  live  hibernated  weevils  was  taken  from  this  field,  so  that 
there  can  be  no  doubt  of  the  presence  of  many  of  them.  The  bags  of 
meal  were  placed  near  apparently  favorable  hibernating  places. 

Fift}T-five  observations  were  made  under  these  conditions,  but  not 
a  weevil  came  to  the  bags  of  meal. 

For  the  second  series  a  field  was  selected  in  which  occasional  seppa 
cotton  plants  were  found.  The  plants  had  been  allowed  to  stand 
through  the  winter  in  this  field,  and  hibernated  weevils  were  quite 
abundant.  The  bags  of  meal  were  here  attached  to  stakes  driven 
beside  seppa  plants.  More  than  50  observations  were  made  after 
weevils  were  known  to  be  out  of  their  winter  quarters.  Nine  weevils 
were  found  upon  the  seppa  cotton  plants  beside  which  the  bags  of 
meal  were  placed,  but  not  a  weevil  was  found  on  the  meal. 

Only  one  conclusion  can  be  drawn  from  these  experiments.  Under 
no  conditions  will  cotton-seed  meal  serve  as  a  food  for  the  weevils, 
and  it  shows  no  power  whatever  of  attracting  them. 

THE  POSSIBILITY  OF  BAITING  WEEVILS  WITH  SWEETS. 

ATTRACTIVENESS   OF   VARIOUS   SWEETS. 

On  account  of  the  considerable  publicity  given  the  theory  that  it 
might  be  possible  to  destroy  the  weevil  \>y  attracting  it  to  sweetened 
poisons,  a  number  of  experiments  were  performed  along  this  line. 


68 

In  the  course  of  this  work  Mr.  <i.  II.  Harris  employed  in  Ihe  labors 
tory  tests  s  Large  variety  of  sweets.  White  granulated  sugar,  two  or 
t  li  pee  grades  of  brown  Bugar,  two  or  three  grades  of  molasses,  and  the 
best  strained  hone}  were  among  the  Bweets  tried.  The  conditions 
were  such  as  to  lead  the  weevils  to  eal  the  sweets  if  thej  would  ever 
do  so.  The  only  alternative  offered  them  for  food  wasa  supply  of 
rather  <>1<|  cotton  Leai es  such  as  weevils  never  t<>u<-ii  in  the  field.  In 
spite  of  the  unfavorable  conditions  for  getting  al  the  real  choice  of 
the  weevils  theyshowed  Little  inclination  bo  feed  upon  the  Bweets 
except  in  the  case  of  honey,  which  seemed  to  attract  them  quite 
Btrongly.  .Manx  weevilsfed  upon  the  unattractive  Leaf  tissue  or  upon 
the  broken  end  of  the  petiole  rather  than  upon  the  sweets. 

The  result  of  Mr.  Harris's  experiments  with  undiluted  molasses 
applied  to  plants  in  the  field  as  summed  up  in  his  own  words  was  that 
"nothing  indicated  that  the  weevils  were  attracted  by  the  odor  of 
sweets."  Honey  was  then  tried,  and  this  did  attract  a  few  weevils. 
Mr.  Harris's  general  conclusion,  based  upon  the  results  of  his  experi- 
ments, was  that  "while  a  high  grade  of  sweets  seemed  to  have  more 
attraction  than  a  cheaper  grade,  neither  can  be  depended  upon  to 
attract  the  weevils  for  poisoning." 

ATTRACTIVENESS  OF  SWEETS  TO  HIBERNATED  WEEVILS  IN  LABORATORY. 

The  sweets  used  in  these  tests  were  of  three  kinds:  High-grade 
molasses,  common  molasses,  and  light-brown  sugar.  The  weevils 
were  brought  in  from  the  field  and  left  for  one  week  without  food  or 
drink  previous  to  the  beginning  of  the  tests  on  April  2,  1903.  Three 
weevils  were  used  with  each  kind  of  sweet,  the  latter  being  in  their 
strongest  form  and  the  sugar  in  a  saturated  solution.  The  inclosing 
apparatus  was  formed  by  placing  two  bottles  mouth  to  mouth  with 
sufficient  space  for  air,  but  not  enough  for  the  escape  of  the  weevils 
between  them.  In  the  bottom  of  one  bottle  was  placed  the  sweet  and 
the  second  leaves  of  cotton  in  the  bottom  of  the  other.  The  weevils 
were  then  inclosed,  and  the  cages  thus  formed  were  placed  in  a  hori- 
zontal position  in  the  dark  to  eliminate  every  possible  influence  of 
direction  of  light,  relative  elevation  of  food,  etc.  The  food  suj)plies 
were  renewed  occasionally,  and  the  location  of  the  weevils  relative  to 
the  food  in  each  cage  was  noted  frequently.  The  weevils  were  counted 
at  eacli  observation.  The  results  of  these  observations  are  briefly 
summarized  in  the  following  table: 

Table  XII. — Attraction  of  various  streets  us.  cotton,  second  leaves. 


Character  of  sweet. 

Number 
of  ob- 
serva- 
tions. 

Number 
of  wee- 
vils on 
cotton. 

Number 
of  wee- 
vils at 
sweets. 

Best  molasses,  cage  1 

20 
13 

18 

86 

29 
42 

48 

1 

Best  molasses,  cage  2. . 

5 

Common  molasses,  cage  3 

4 

Brown-sugar  sirup,  cage  4 

Total 

21 

8 

72 

144                  1« 
144 

54 

These  figures  become  even  more  striking  in  consideration  of  the 
fact  that  the  cotton  leaves  were  often  purposely  left  until  they  became 
moldy  and  decayed  or  dried  and  wholly  unfit  for  food.  It  was  at 
such  times  that  most  of  the  weevils  sought  the  sweet  in  preference. 
Should  we  leave  out  of  the  account  the  weevils  found  at  the  molasses 
or  sirup  when  the  cotton  was  unfit  for  food,  the  number  attracted 
there  would  be  reduced  fully  one-half.  In  either  case  the  fact  remains 
that  none  of  the  sweets  can  be  said  to  have  attracted  weevils  from 
the  cotton  leaves. 

INFLUENCE    OF   SWEETENED   WATER    UPON    FEEDING   OF   WEEVILS   ON 

COTTON  PLANTS. 

It  is  easy  to  demonstrate  that  weevils  will  in  confinement  feed 
upon  sweet  solutions.  To  prove  that  they  will  show  the  same  attrac- 
tion to  it  in  the  field  is  a  far  more  difficult  matter. 

For  the  purpose  of  these  experiments,  cheap  molasses  was  used, 
mixing  1  part  of  molasses  with  25  parts  of  water,  as  is  generally 
recommended  in  spraying  formula3.  Three  pairs  of  young  plants 
which  had  not  begun  to  square  were  then  selected  from  those  growing 
upon  the  laboratory  grounds.  The  plants  in  each  pair  were  of  equal 
size,  and  both  in  healthy  condition  and  standing  closely  enough 
together  to  be  both  covered  by  one  cage.  One  plant  of  each  pair  was 
then  dipped  in  the  sweetened  water,  while  the  other  was  left  in  its 
natural  condition.  In  each  of  the  cages  10  weevils  were  then  placed 
upon  the  ground  and  midway  between  the  bases  of  the  plants.  The 
object  of  the  test  was  to  see  which  plant,  the  treated  or  untreated, 
would  attract  the  larger  number  of  weevils.  During  the  first  three 
days  observations  were  made  several  times  each  day.  Weevils  found 
upon  either  plant  were  counted  at  each  observation. 

A  summary  of  the  observations  made  on  the  first  day  before  the 
liquid  had  dried  showed  15  weevils  upon  the  sweetened  plants  and  16 
on  those  not  sweetened.  These  results  were  so  remarkably  even  that 
no  attraction  or  repulsion  could  be  ascribed  to  the  liquid  before  it 
dried. 

During  the  ten  days  covered  by  the  observations,  however,  63  wee- 
vils were  found  upon  the  unsweetened  plants  and  only  45  upon  those 
sweetened.  The  weevils  fed  largely  upon  the  petioles  and  somewhat 
upon  the  blades  of  the  leaves  and  the  main  stems  of  the  plants.  No 
indication  was  observed  of  special  feeding  upon  the  "gloss"  left  by 
the  drying  of  the  sweetened  water.  In  each  cage  the  normal  untreated 
plant  was  destroyed  before  the  treated  one.  During  the  first  half  of 
the  observations  52  weevils  were  found  feeding  upon  the  unsweetened 
plants  and  only  32  upon  the  sweetened.  Only  after  every  leaf  on  the 
untreated  plants  hung  black  and  dead,  while  the  sweetened  plants 
were  in  much  better  condition,  did  more  weevils  attack  the  sweetened 
plants. 


Not  <»iil\  »l  i<l  these  tests  shoM  that  molasses  in    olution  has  no  attrac 
iion  for  ili«'  weevils,  but   also  that   the  stick}  coating  left  after  the 
liquid  lias  dried  acts  more  as  a  positive  repellant  to  them. 

FIELD   TESTS    FOR    HIBERNATED    WEEVILS,  USING    PI  1:1     HOLA      I 

As  a  final  experiment  t<>  settle  the  possible  usefulness  of  mola 
in  the  weevil  fight,  a  large  series  of  tests  was  undertaken  in  ih<-  i i < - 1 « ! 
to  see  If  the  pure,  undiluted  molasses  would  noi  prove  attractive  to 
\ur\  Lie  as  they  came  from  hibernation.  To  insure  a  continuous  sup- 
ply of  fresh  molasses  a  test  tube  was  nearly  filled  and  then  rather 
tightly  plugged  with  a  small  stopper  wound  with  cotton.  The  tube 
was  then  fastened  in  an  inverted  position  to  the  top  of  a  stake  about 
•J  feet  Long,  and  as  the  molasses  gradually  oozed  through  the  cotton 
it  ran  slowly  down  Ihe  stake,  forming  a  streak  of  continuously  fresh 
molasses  a  foot  or  more  in  Length.  The  supply  would  thus  last  for 
several  days  and  was  then  easily  replenished.  This  apparatus,  as 
shown  in  PI.  XII,  fig.  45,  was  then  placed  beside  a  vigorous  seppa  cot- 
ton plant  in  the  field  at  the  season  when  the  weevils  were  beginning 
to  leave  their  winter  quarters  and  seek  food  to  break  their  Long  fast. 
Both  high  and  Low  grades  of  molasses  were  employed  in  these  tests, 
three  t  ubes  of  each  being  used.  Altogether  84  observat  Lonswere  made 
between  April  24  and  .May  15,  11)03,  during  which  period  most  of  ihe 
weevils  emerged  from  hibernation. 

The  results  again  proved  disappointing,  for  only  a  single  weevil 
was  ever  found  at  the  molasses.  This  individual  sipped  occasionally 
at  the  sweet,  wandering  up  and  down  the  tube  in  the  intervals.  It 
did  not  appear  to  be  satisfied  and  did  not  remain  long  at  or  near  the 
molasses,  but  flew  away  and  was  not  found  there  again. 

The  failure  of  the  molasses  to  attract  was  not  due  to  the  scarcity  of 
weevils  in  the  field.  During  the  period  of  observation  23  weevils 
were  found  working  upon  seppa  cotton  very  near  the  molasses  tubes, 
and  certainly  within  reach  of  its  attractive  influence,  provided  it  had 
any.  More  weevils  were  also  found  in  the  same  field,  but  at  some- 
what greater  distances  from  the  tubes. 

During  the  warm  days  toward  the  close  of  the  experiment  many 
butterflies,  mostly  Vanessa  atalanta  and  some  Anosia  plexippus,  came 
to  the  tubes.  A  few  specimens  representing  several  species  of  beet  les 
and  many  ants  Avere  also  found. 

None  of  the  experiments  made,  either  in  the  laboratory  or  in  the 
field  at  Victoria,  Tex.,  has  shown  that  weevils  are  attracted  in  even 
the  slightest  degree  to  any  grade  of  molasses,  either  in  its  undiluted 
or  diluted  form.  No  sugar  solution  has  been  found  to  possess  any 
more  attraction  than  does  molasses.  Honey  appears  to  be  an  espe- 
cially attractive  sweet,  but  is  too  expensive  for  use  in  this  manner. 

Considering  the  facts  that  these  experiments  have  been  much  more 
numerous  and  that  they  have  covered  a  much  broader  range  of  con- 


56 

ditions  tlian  any  previously  performed,  we  must  conclude  that  it  yet 
remains  to  be  shown  that  sweets  of  any  kind  have  any  value  in  the 
problem  of  controlling  the  boll  weevil. 

FEIGNING  DEATH. 

This  interesting  habit  of  the  weevil  is  its  first  resort  as  a  means  of 
escape  from  its  larger  enemies.  It  has  been  the  basis  of  many  ma- 
chines designed  to  jar  them  from  the  plants  and  to  collect  them  in 
convenient  receptacles.  If  jarred  from  the  plant,  the  weevil  falls  to 
the  ground,  with  its  legs  drawn  up  closely  against  the  body  and  the 
antennre  retracted  against  the  snout,  which  is  brought  inward  toward 
the  legs.  The  position  is  characteristic  and  can  be  more  easily  shown 
than  described.  See  PI.  I,  fig.  2.  In  this  position  it  often  remains 
motionless  for  some  time.  If  further  disturbed,  so  that  it  finds  that 
its  ruse  has  failed  to  conceal  it,  it  will  start  up  quickly,  run  a  little 
way,  and  again  fall  over,  feigning  death.  The  color  of  the  weevil 
so  closely  resembles  that  of  the  ground  that  it  is  quite  difficult  to  find 
a  fallen  individual  so  long  as  it  remains  quiet.  The  habit  is  of  great 
value  in  protection.  If  left  undisturbed  until  it  believes  danger  to 
be  past,  it  recovers  its  footing  and  returns  to  the  plant. 

REPRODUCTION. 

Under  this  general  heading  we  present  some  of  the  most  interesting 
observations  which  have  been  made  upon  the  habits  of  the  boll  wee- 
vil. The  relation  of  the  sexes,  the  evident  selection  of  clean  squares 
for  egg  deposition,  the  great  destructive  power  of  the  weevil,  the 
rapiditj-  of  development,  and  the  influence  of  varying  temperatures 
upon  its  activity  and  development  may  also  be  classed  as  among  the 
most  important  as  well  as  most  interesting  observations. 

METHOD   OF  MAKING  FIELD   OBSERVATIONS  UPON  WORK  OF 

WEEVIL. 

For  the  purpose  of  field  study  large  cages  (3  by  3  by  4  feet)  were 
made,  the  covering  being  of  fine  wire  screening  (PI.  IX,  fig.  36). 
Uninfested  plants  having  plenty  of  squares  were  found  by  a  careful 
examination  of  each  square  and  inclosed  by  the  cages.  The  number 
of  weevils  placed  in  each  cage  was  varied  according  to  the  number  of 
squares  within,  ranging  from  2  to  5  at  various  times.  In  making  the 
daily  observations  the  cage  was  entered  and  each  square  examined. 
Each  square  found  attacked  in  an}7  way  was  marked  with  a  numbered 
tag  containing  full  data  as  to  the  lot  of  weevils  and  the  number  pres- 
ent, date,  and  nature  of  injury  (PI.  IX,  fig.  37).  After  all  weevils 
had  been  found  the  cages  were  removed  to  new  uninfested  plants  for 
another  day's  work.  Close  watch  was  kept  upon  all  tagged  squares 
upon  succeeding  days,  and  every  important  change  taking  place  in 
each  square  was  added  to  the  record  on  the  tag.     The  special  points 


Platt  VIII. 


External  and  Internal  Injury  from  Feeding  on  Bolls. 

Fig.  34,   External  appearance  of  large  boll  much  fed  upon,  natural  size:  tig.  35,  internal  appear- 
ance of  same  boll,  natural  >i/e.     ,  < Original,  i 


• 


I 


Fiq.  36.— Cages  Used  to  Confine  Weevils  in  Field.    (Original). 


Fig.  37.— Plant  Showing  Tagged  Squares  from  Cage  Work.     'Original,  i 


i 


p 


Egg  and  Feeding  Punctures:  Effects  on  Squares  and  Bolls. 

Fig.  38,  lioll  showing  two  locks  destroyed  by  two  feeding  punctures  made  by  a  male  weevil,  two- 
thirds  natural  size:  tii.r.  39,  square  showing  external  appearance  of  two  egg  punctures,  natural 
size:  fig.  40.  wart  formed  on  side  of  square  in  healing  an  egg  puncture,  natural  size:  fig.  11.  egg 
deposited  on  inside  of  carpel  of  a  boll,  two-thirds  natural  size:  fig.  12,  normal  ami  flared 
squares,  natural  size.     (Original.) 


noted  in  each  case,  bo  far  as  was  possible,  were:  The  formation  of  a 
distinct  wart;  time  of  flaring,  yellowing,  and  falling;  the  emergence 
of  adult;  presence  of  a  parasite;  death  of  larva,  pupa,  etc.  A  very 
complete  historj  of  each  square  was  thus  obtained.  During  the  sea 
son  of  1903  three  Bpecial  periods  wen-  selected  for  stud}  of  this  kind. 
The  first  was  taken  during  the  early  pari  of  June,  when  hibernated 
weevils  only  were  active,  the  second  was  taken  in  August  for  the 
work  in  midsummer,  and  the  third  in  the  latter  part  of  October  for 
the  Btudy  of  the  development  of  lat<-  weevils.  Altogether  in  these 
three  series  over  a  thousand  squares  were  tagged  and  recorded.  The 
work  of  males  was  compared  with  that  of  females  in  this  way,  as 
were  also  the  developmental  periods  in  squares  and  bolls.  Although 
requiring  a  great  deal  of  time  and  close  attention,  the  numerous  defi- 
nite observations  obtained  abundantly  justified  the  work  required. 

FERTILIZATION. 
AGE   OF   BEGINNING    COPULATION. 

After  the  adult  weevils  have  left  the  squares  a  certain  period  of 
feeding  is  necessary  before  they  arrive  at  full  sexual  maturity.  This 
period  varies  in  Length  according  to  the  effective  temperature  prevail- 
ing and  appears  to  bear  about  the  same  ratio  to  the  developmental 

period  as  does  the  pupal  stage. 

Among  the  many  weevils  kept  from  emergence  till  death  for  the 
purpose  of  ascertaining  the  length  of  life  without  food,  copulation 
was  never  observed.  With  weevils  fed  upon  leaves  alone  the  period 
preceding  copulation  is  about  twice  the  normal  length  in  the  cases 
observed  of  those  having  squares  to  feed  upon. 

During  the  hot  weather  this  period  appears  to  be  on  the  average 
only  about  three  or  four  days  in  length,  while  as  the  weal  her  becomes 
colder  it  increases  gradually  until  weevils  may  become  adult,  feed 
for  a  time,  and  go  into  hibernation  without  having  mated.  '  A  single 
union  seems  to  insure  the  fertility  of  as  many  eggs  as  the  average 
female  will  lay,  and  its  potency  certainly  lasts  for  a  period  fully  equal 
to  the  average  Length  of  life. 

SEXl'Ai.    ATTRACTION    AND    DURATION    OF   COPULATION. 

The  distance  through  which  the  attraction  of  the  female  will  influ- 
ence the  male  varies  extremely.  To  ascertain  how  far  the  attraction 
might  be  exerted  in  the  case  of  the  "boll  weevil,  2  females  were  con- 
fined with  food  in  a  small  bottle  covered  with  cheese  cloth,  and  the 
bottle  was  then  placed  in  a  horizontal  position  inside  a  Held  cage  and 
near  its  top.  Within  this  cage  were  3  males  which  had  been  confined 
there  alone  for  4  weeks.  The  bottle  containing  the  females  was  so 
placed  as  to  be  within  a  tew  inches  of  the  top  of  a  cotton  plant  upon 


58 

which  the  males  were  working  and  touching  the  leaves  of  the  plant, 
in  order  to  afford  the  males  access  to  the  bottle  without  having  to  fly 
to  it. 

Close  watch  was  kept,  but  during  11  days  not  a  male  was  seen  to 
go  near  the  bottle.  At  the  end  of  that  time  the  females  were  taken 
into  the  laboratory,  as  was  also  one  of  the  males  from  the  cage.  All 
were  removed  from  squares  and,  being  placed  upon  the  table,  were 
brought  gradually  nearer  together.  The  male  paid  no  attention 
whatever  to  the  nearest  female  until  brought  within  an  inch  of  her. 
He  then  went  directly  to  her.  The  sense  of  smell  appeared  to  guide 
his  movements.  The  fact  that  this  male  mated  readily  with  both  of 
the  females  used  in  the  cage  shows  that  the  only  reason  for  failure  t  o 
attract  in  the  cage  lay  in  too  great  distance  separating  the  sexes. 

These  observations  are  entirely  borne  out  by  those  made  in  the 
field.  The  fact  appears  to  be  that  the  sexes  are  attracted  only  when 
they  meet  either  on  the  stems  or  upon  the  squares  of  a  plant.  The 
comparative  inactivity  of  the  male  has  a  bearing  on  this  matter. 
The  general  conclusion  is  that  instead  of  seeking  widely  for  the 
females,  the  males  are  content  to  wait  for  them  to  come  their  way. 
The  greater  comparative  activity  of  females  is  shown  in  the  stud3T  of 
their  food  habits. 

In  a  number  of  cases  that  were  timed  the  average  duration  of  the 
sexual  act  was  very  nearly  thirty  minutes. 

DURATION   OF   FERTILITY   IN   ISOLATED   FEMALES. 

A  number  of  females  which  were  known  to  have  mated  were  isolated 
to  determine  this  point.  Although  neither  limit  was  exactly  deter- 
mined, the  results  proved  veiy  striking.  Several  of  these  females 
laid  over  225  eggs  each  and  nearly  all  of  them  proved  fertile.  Select- 
ing three  cases  in  which  the  facts  are  positively  known,  it  appears  that 
fertility  lasted  for  an  average  of  something  over  GO  days  and  that 
during  this  period  these  females  deposited  an  average  of  nearly  200 
eggs.     The  maximum  limits  may  possibly  be  considerably  higher  than 

these. 

OVIPOSITION. 

AGE   OF   BEGINNING   OVIPOSITION. 

Normal  oviposition  seems  never  to  take  place  until  after  fertiliza- 
tion has  been  accomplished,  but  it  usually  begins  soon  after  that. 
Observations  upon  the  age  at  which  the  first  eggs  are  deposited  can 
be  made  more  easily  and  more  positively  than  those  upon  the  age  at 
which  fertilization  takes  place.  In  a  general  way,  therefore,  the 
observations  here  given  may  be  considered  as  also  throwing  light 
upon  the  time  of  beginning  copulation. 

In  the  breeding  of  weevils  from  eggs  deposited  by  hibernated  females 
a  number  of  observations  accumulated  upon  this  point  and  another 
series  was  made  in  the  fall  of  1902.  The  results  of  both  series  are 
given  in  Table  XIII. 


59 

Tabli    XIII.       !'/•  of  beginning  ovijwmt ion. 
WEEVILS  I  »r  FIRST  OENERATK  IN,  1908. 


Date  adult 

Date  of  th-st  egg. 

Number 

..i  i. 
malefl 

i 
time 

9  ii 

'.Ml 

.-,  o 

I   ii 

7.0 

5.0 

id 

1908. 
.1  one  R  to  9 

1908 
June  \!i  t..  18 

:f 
l 

i 

i 

i 

June  in 

.linn'  I'.i 

'.i  ii 

.lllll.'    II 

.Inn.-  18 

:■:,  ii 

do 

1  II 

Do 

.luii.-  I'.' 

III) 

June  13 

June  i'- 

50 0 

June  13  t<>  1 1                                                 

.i..             

85  'I 

.1.,            

16  H 

Total 

27 



150  ii 

WKKVILS  BRED  IN  FALL  <»F  imr.'. 


1908. 

September  4  to  5 . . 

1902. 

September  17 

September  16 

October  16. 

November  \r>  to  17... 
November  l'.i 

8 

•") 

4 

3 

12.5 

7.(1 
14.0 
7.0 

8  ii 

87.5 

September  9 

35.0 

October  2 

56.0 

November  9 1  >ll                      

49.0 

November  11 

24.0 

Total 

22 

801.5 

«».<)+ 

The  average  time  of  5.5  days,  as  shown  by  the  firsi  generation,  is 
probably  about  a  day  and  a  half  longer  than  the  minimum  average 

period  during  the  hottest  weather,  while  the  9-day  average  found  from 
September  4  to  November  11  is  considerably  short  of  the  maximum 
average  just  before  hibernation. 

EXAMINATION   OF   SQUARES   BEFORE    OVIPOSITION. 

In  the  course  of  a  great  many  observations  upon  oviposition  it 
was  found  that  females  almost  invariably  examine  a  square  quite 
carefully  before  they  will  begin  a  puncture  for  egg  deposition.  This 
examination  is  conducted  entirely  by  means  of  senses  located  in  the 
antennse  and  not  at  all  by  sight.  In  fact,  the  sense  of  sight  appears 
to  be  of  comparatively  small  use  to  the  weevil. 

In  regard  to  the  actual  time  spent  in  the  work  of  examination  before 
beginning  a  puncture  60  observations  were  recorded.  These1  show 
that  the  average  time  is  over  two  minutes. 

This  examination  of  squares  is  made  by  females  only  when  they 
intend  to  oviposit.  Males  have  never  been  observed  acting  in  this 
way,  nor  do  females  generally  do  so  when  their  only  object  is  to  feed. 

SELECTION    OF    UNINFESTED   SQUARES    FOR    OVIPOSITION. 

So  unerring  is  the  sense  by  which  examination  is  made  that  in  a 
few  cases  it  was  able  to  discover  an  infested  condition  no  external  sign 
of  which  was  visible  to  the  writer's  eye.  A  female  which  was  under 
elose  observation  examined  the  square  given  her  in  the  usual  manner, 
but  though  evidently  searching  for  a  place  to  oviposit  and  anxious  to 


60 

do  so,  she  plainly  objected  to  placing  an  egg  in  that  particular  square 
The  writer  again  examined  the  square  carefully,  but  found  no  sign  of 
infestation  and  replaced  it  in  the  observation  cage.  Again  the  female 
made  her  usual  careful  examination  and  still  she  plainly  refused  to 
oviposit.  Upon  removing  the  covering  from  the  square  it  was  found 
to  contain  an  egg^  but  the  puncture  made  in  depositing  it  had  healed 
so  smoothly  that  it  had  thrice  escaped  observation.  The  same  female 
was  then  given  two  squares,  one  of  which  was  known  to  be  infested, 
the  latter  being  placed  nearer  her.  She  examined  it  carefully,  then 
left  it,  and  went  at  once  to  the  clean  square,  in  which,  after  the  usual 
examination,  she  deposited  an  egg. 

The  acuteness  and  accuracy  of  the  preliminary  examination  is  also 
well  shown  by  the  fact  that  when  provided  with  more  squares  than 
they  have  eggs  to  deposit  they  rarely  place  more  than  one  egg  in  a 
square.  It  was  frequently  found,  however,  that  when  a  female  depos- 
ited just  as  maii3T  eggs  as  there  were  squares  present  she  would  place 
two  eggs  in  one  and  then  make  only  feeding  punctures  in  the  remain- 
ing square. 

The  observations  were  made  upon  a  large  number  of  females;  so 
there  can  be  no  doubt  that  the  habit  of  selection  is  general.  The 
conditions  provided  in  these  experiments  were  intended  to  resemble 
those  existing  in  a  slightly  infested  field  early  in  the  season,  where  each 
female  could  easily  find  an  abundance  of  clean  squares  in  which  to 
deposit  her  eggs.  Therefore  only  those  cases  were  recorded  in  which 
the  number  of  squares  present  equaled  or  exceeded  the  number  of 
eggs  deposited.  Where  a  totally  infested  condition  is  reached  no 
choice  between  infested  and  uninfested  squares  could  be  exercised, 
and  then  unless  the  female  happened  to  be  in  a  condition  to  refrain 
from  oviposition  she  would  be  forced  to  deposit  more  than  one  egg 
in  a  square. 

Not  only  do  females  show  a  strong  inclination  to  place  only  one  egg 
in  each  square,  but  the}'  also  object  to  making  both  egg  and  feeding 
punctures  in  the  same  square.  That  these  conclusions  are  well 
grounded  may  best  be  shown  by  giving  a  summary  of  two  long  series 
of  observations,  the  first  made  in  the  laboratory  in  the  fall  of  1902 
and  the  other  made  in  the  field  partly  in  the  fall  of  1902  and  partly  in 
the  spring  of  1903. 

LABORATORY   OBSERVATIONS. 

Nine  females  were  used  in  this  series  of  experiments.  The  time 
followed  varied  with  each  individual,  but  ranged  from  October  23  to 
December  18,  1902.  During  this  period  a  total  of  868  uninfested 
squares  was  supplied  to  these  9  females.  Of  these  squares  238  were 
not  touched,  while  630  were  punctured,  either  for  oviposition  or  for 
feeding  or  for  both.  The  general  results  are  here  summarized  in 
tabular  form. 


61 


Tabi  i    XIV.     s*  lection  of  mptarea  and  relation  oj  feeding  to  <>ri/„, 


So 

Of  !■■ 

male. 

Period  of  obeer\  ation. 

Square! 
supplied 

Squares 

with  1 

Squarei 

with  8 

Square! 

fed  "ii 
onlj 

Bquai 
with       Square! 

Ix.th              ini 
ind  touched, 
ng. 

l 

:\ 

i 

8 

. 

8 
9 

1900. 
»  October  88  t<>  November  16 
October  88  to  Novemtx 
( fctober  'J">  t<>  November  '< 
( October  23  to  I  tetober  88 
« tetober  ~':;  to  <  tetober  88 
N..\  ember  m  to  1  December  5 
November  10  to  N"\  ember  85 
N'..\  ember  in  t<>  December  18 
November  1 1  t « >  December  12 

Total 

L86 
171 
96 

91 

L07 

128 

108 

".i 
18 
:«i 
■M 
41 
L8 
68 

i 

I 

0 

i 
ii 

8 

1 
8 

6 

■ 

I 

18 
16 

I 

7 
1 
I 

1 
1 
1 
6 

81 

g 

g 

8 

-,i 

16 

477 

19 

lln 

.V  Little  calculation  from  these  results  shows  thai  82.5+  IM''*  ('(>|11  (,1 
all  squares  attacked  received  eggs  and  thai  91.7+  per  cenl  of  all 
squares  oviposited  in  received  only  one  egg  each.  The  squares  which 
were  fed  upon  only  formed  17.5—  per  cent  of  the  total  number 
attacked,  aud  those  receiving  both  egg  and  feeding  punctures  consti- 
tute only  3.8  per  cent.  The  squares  receiving  two  eggs  each  also  form 
3.8  per  cent  of  all  the  squares  which  received  eggs  only. 

The  tendency  to  confine  egg  and  feeding  punctures  to  separate 
squares  is  strongly  emphasized  by  the  fact  that  in  17  instances,  in 
which  a  total  of  116  squares  was  provided,  91  received  eggs  only,  while 
the  remaining  25  were  fed  upon  only;  another  total  of  78  squares 
received  88  eggs  in  72  of  them,  while  the  remaining  6  were  fed  upon 
only.  As  these  two  lots  include  nearly  one-third  of  all  the  squares 
punctured,  the  tendency  may  be  clearly  seen. 

FIELD    OBSERVATIONS. 


For  one  series  of  observations  500  infested  squares  were  picked 
promiscuously  in  the  field  between  May  28  and  June  9,  1903. 

A  previous  field  examination  was  made  about  the  middle  of  Septem- 
ber, 1002,  and  this  furnishes  some  very  interesting  comparisons  as  to 
the  weevil's  work  upon  the  squares,  especially  at  the  beginning  of  the 
infestation  and  after  it  had  reached  its  height.  To  facilitate  an  easy 
comparison,  the  results  are  arranged  in  Table  XV. 


62 

Table  XV. — General  results  of  observations  upon  selection  of  squares. 


£ 
M 

3 

7a 

c 

Squares  with 
1  egg  each. 

Squares  with 
more  than 
1  egg  each. 

Squares  with 

Wh  egg 
and  feeding 
punctures. 

Squares  fed 

on  only. 

S 

Percentage  of 
all   squares 
receiving 
eggs. 

0 

| 

o  a 

0>  c3  P 
Ah 

<s> 
A 
3 
pi 
ft 

©s 

i 

a 

9 

0  cc 
II 

©•g 

Squares  infested  in  laboratory 
Oct.  23  to  Dec.  2, 1903 

Squares  picked  in  field  May  28  to 
June  9,  1903 

Squares  picked  in  field  Sept.  17  to 
22,1902 

630 

500 
105 

477 

317 

56 

91.7 

79.2") 

62.9 

19 
83 
33 

3.8 
20.75 
37.1 

24 
50 
46 

3.8 
10.0 
43.8 

110 
110 
16 

17.5 
20.0 
15.2 

Total 

1,235 

850 

"84.y 

135 

...... 

"iO" 

120  i. 

97 

236 

Average  percentage 

18.3 

' 

A  few  obvious  conclusions  may  well  be  stated  here.  Throughout 
the  season  from  one-fifth  to  one-sixth  of  the  squares  injured  were 
destroyed  by  feeding  punctures  alone.  Within  this  small  portion 
must  be  included  most  of  the  work  of  males  and  also  of  newl3~ 
emerged  females  before  they  reach  sexual  maturity.  As  the  weevil 
injury  overtakes  the  production  of  squares  it  becomes  increasingly 
difficult  for  females  to  find  clean  squares,  and  they  are  forced  to 
deposit  eggs  in  squares  already  injured  and  also  to  feed  upon  squares 
which  already  contain  eggs.  These  conditions  serve  to  increase  most 
rapidly  the  proportion  of  squares  containing  both  egg  and  feeding 
punctures.  This  is  still  further  emphasized  by  the  fact  that  in  June 
onty  30  per  cent  of  all  injured  squares  contained  feeding  punctures, 
while  in  September  nearly  60  per  cent  had  been  thus  injured.  When 
females  have  access  to  an  abundance  of  squares,  they  will  deposit 
more  than  one  egg  onl}T  in  about  one-fifth  of  those  in  which  they  ovi- 
posit, while  the  proportion  of  those  having  both  egg  and  feeding 
punctures  is  still  smaller. 

The  tendencies  to  keep  egg  and  feeding  punctures  separate,  as  well 
as  to  deposit  only  one  egg  in  a  square,  serve  to  produce  the  greatest 
injury  of  which  the  weevils  are  capable  for  two  obvious  reasons :  First, 
because  where  several  eggs  are  placed  in  one  square  it  is  rarely  the 
case  that  more  than  one  larva  develops.  If  two  or  more  hatch  in  a 
square,  one  is  likely  to  destroy  the  others  when  their  feeding  brings 
them  together.  They  bite  savagely  at  anything  which  irritates  them, 
and  larvae  have  been  found  in  the  actual  death  struggle.  Second, 
should  eggs  be  placed  in  squares  which  already  contained  a  partly 
grown  larva,  those  hatching  would  likely  find  the  quality  of  the  food 
so  poor  that  they  would  soon  die  without  having  made  much  growth. 
One  egg  will  insure  the  destruction  of  the  square,  and  a  number  of 
eggs,  could  all  the  larvae  live,  would  do  no  more.  Therefore  it  is 
plain  that  the  possible  number  of  offspring  of  a  single  female  is 


c:; 

increased  directly  in  proportion  to  the  number  of  her  eggs  that  she 
places  one  in  a  square,  and  favorable  Pood  conditions  for  the  larva 
are  best  maintained  by  avoiding  feeding  upon  squares  in  which  • 
have  been  deposited,  and  also  by  refraining  from  ovipositing  in  squares 
which  have  been  much  fed  upon.  These  habits  of  selections  are, 
therefore,  of  the  greatest  importance  in  the  reproduction  of  the  weevil, 
since  thej  insure  ih<i  most  favorable  conditions  for  the  maturity  of 
the  largest  possible  number  of  offspring.  In  ol  her  words,  I  hese  habits 
enable  the  weevil  t<>  do  the  greatest  damage  of  which  it  is  capable 
while  the  cotton  crop  is  "making." 

These  habits  are  perhaps  less  strongly  marked  in  the  case  of  l><>lls, 
though  st  ill  plainly  manifested.  Feeding  and  oviposit  ion  are  common 
in  the  same  boll,  but  unless  the  infestation  is  very  great  indeed  it 
appears  that  only  rarely  is  more  than  one  egg  placed  in  one  lock, 
though  several  are  often  deposited  in  the  same  boll.  The  number  de- 
posited depends  considerably  upon  the  size  of  the  boll.  The  smallest, 
which  have  just  set,  receive  but  one,  as  do  the  squares,  and  these  fall 
and  produce  the  adult  weevil  at  about  the  same  period  as  in  the  case 
of  squares.  Bolls  which  are  larger  when  they  become  infested  are 
often  found  to  be  thickly  punctured  and  sometimes  contain  6  or  8 
larvae.  The  weevil  seems  to  know  when  the  food  supply  is  sufficient 
to  support  a  number  of  larva'  and  deposits  eggs  accordingly. 

ACTIVITY    OF    WEEVILS   IN   DIFFERENT   PARTS   OF   THE    DAY. 

The  5  females  used  in  these  tests  were  kept  in  a  field  cage  on  pre- 
viously uninfested  plants,  and  examinations  of  their  work  were  made 
mostly  at  four-hour  intervals  from  G  a.  m.  to  6  p.  m.  The  exact  work 
found  was  recorded  upon  tags  attached  to  the  squares  themselves. 
Temperature  readings  were  taken  at  the  same  time  as  the  observa- 
tions.    The  results  are  most  clearly  presented  in  tabular  form  (p.  64). 


64 


Table  XVI. — Activity  of  jive  weevils  in  differt  at  parts  of  the  <l<i;/. 


Date. 

Period. 

Tem- 
pera- 
ture. 

T. 

Ti 

:  - 

r 

be 

'. 

:§ 
at 

bo 

c 

'S  . 
-  •/. 

4  £ 

~  z      Condition  of 
;  g           weevil    ut    end 
fed          of  period. 

,2  B 

-'- 

Remarks. 

1909. 

Sept,  2 

Sept.  2-3.- 

Sept.3 

Do 

Do 

Sept.  3  !___ 

Sept.  i..... 

Do 

Do 

93-60 

80-69 

69-*5 

85-95 
95-64 

84-68 

68-63 

83-91 
91-62 

82-79 

IB 

:; 

12 

18 
12 

3 

4 

24 
11 
5 

15 

1 

10 

15 
11 

1 

1 

19 

8 

(i  p.  in.  to  6  a.  m 

6.15  to  10.15  a.  m 

10.40  a.m.  to  2.40p.m. 
3 to 6.30 p. m  ..- 

6.30  p.m. to 6  a.m. 

6.30  to  10a. m 

10  a.m.  to 4  p. m 

4  to6p.m 

(5  p.m.  to  9a. m 

Total 

2 
2 

10 
6 

3 

4 
12 

plant. 
All  resting 

All  active 

do 

Placed  on  fresh 

plant. 
All  resting 

3  moving  to  ad- 
jacent squares. 
All  active 

Punctures    black 

at  6  a.m. 
3  trying  to  escape; 

cage  moved. 
( Jage  moved. 

Feeding   punc- 
tures all  black; 
small    square 
flared. 

Sept.  4-5..  _ 

0           6 

All  feeding 

Cloud v:    every 
wtevil  on  same 
square  as  at  6 
p.  m. 

108 

81 

60 

An  examination  of  these  figures  shows  that  weevil  activity  began 
and  ceased  at  about  75°  F.  Activity  increased  as  the  temperature 
rose,  and  its  maximum  coincided  with  the  maximum  of  dailv  tern- 


FAHREN- 
HEIT 

TIME 

12 p  Iam    2      3    4     5     6     7     8     9     10     II    12m  Ipm   2     3    4     5     6    7     8     9     10    II    I2p 

100° 
95° 
90° 
85° 
80° 
75° 
70° 
65° 
60° 

1 

1 

.  \\ 

pji 

//// 

rf| 

^<^. 

4 

K' 

' 

NV. 

/ 

/  / 
/ 

\ 

7. 

$ 

^^ 

t,„ 

r?tf' 

>rt 

& 

\ 

Or 

*ra 

ye  t 

'Let 

VI 

V  o 

''/'- 

'•/' 

/('// 

ojU 

•w 

■ri- 

lls 

ty— 

0 

vj 

epi 

em 

bei 

'J, 

f  6  . 

;./ 

HK 

Fig.  3. — Diagram  showing  average  activity  of  five  female  weevils.     (Original.) 

perature.  It  then  decreased  with  the  falling  temperature  until  it 
ceased  entirely  some  time  during  the  evening,  probably  at  about 
75°  F.  See  fig.  3.  Feeding  continued  at  lower  temperatures  than 
oviposition,  as  is  known  to  be  the  case  during  the  late  fall. 

Examinations  made  in  the  field  between  6  and  7  a,  m.  on  Septem- 
ber 4  showed  that  all  weevils,  both  males  and  females,  were  quietly 
resting  at  that  time  with  the  temperature  at  about  70°  F.  On  cloudy 
days  the  activity  is  less  than  it  is  on  clear  days. 


■    XI. 


Fig.  43.— Three  Large  Larv/e  in  a  Boll,  Two-thirds  Natural  Size.    'Original.*. 


Fig.  44.— Four  Pupal  Cells  from  Bolls  ion  Left*  Compared  with  Four  Cotton 
Seeds  ion  Rights  Natural  Size.    (Original.) 


Plati    XII. 


Testing  Devices.    Fallen  and  Hanging  Infested  Squares. 

Fig.  15,  Device  used  to  test  attraction  of  molasses  in  the  field  in  the  spring;  fig.  46,  fallen  squares 
on  ground  in  field;  t i lt .  17.  infested  squares  dried  and  still  hanging  upon  the  plant:  fig.  48,  device 
used  to  test  relative  attractiveness  to  weevils  of  American  and  Egyptian  squares.    (Original,  i 


PL  \»  B   OF    i  .1  H  ■    i'i:i'<  >S1  i  n  »v 

The  Location  of  egg  punctures,  while  variable,  >till  shows  some 
selection  on  the  pari  of  the  weevil.  This  maj  be  due  partly  to  the 
form  of  i  he  squares  and  pari  ly  also  to  I  he  size  of  I  h<-  we<  vil,  bu1  w  hal 

e\<  r  the  explanation  the  facl  remains  ihai  in  a  majority  of  cases  the 
egg  puncture  is  made  on  a  line  aboul  halfway  between  the  base  and 
tip  of  the  square.  When  so  placed  the  egg  comes  to  resl  either  jusl 
inside  the  base  of  a  petal  or  among  the  lowest  anthers  in  the  square, 
according  to  the  varying  thickness  of  the  floral  coverings  at  thai 
point  (PI,  I,  fig,  •'!).  Punctures  are  very  rarely  made  below  this  line, 
though  they  are  sometimes  made  nearer  the  tip.  Almost  invariably 
the  egg  puncture  is  started  through  the  calyx  in  preference  to  the 
more  lender  portion  of  the  square,  where  the  corolla  only  would  need 
to  be  punctured.  The  reason  for  the  choice  of  this  location  may  be 
found  under  the  subject  of  the  " Relation  of  warts  to  oviposit  ion,"  on 
page  »'>(.». 

With  bolls  no  selection  of  any  particular  location  has  been  found, 
but  eggs  seem  to  be  placed  in  almost  any  portion.  PL  X,  fig.  41, 
shows  the  egg  deposited  inside  the  carpel. 

POSITION    OF   THE   WEEVIL   WHILE    PUNCTURINO    FOR    OVTPOSITION. 

While  engaged  in  making  c^j;  punctures  the  favorite  position  of 
the  weevil  is  with  its  body  parallel  to  the  long  axis  of  the  square  and 
its  head  toward  the  base  of  the  same.  The  tip  of  the  weevil's  body 
is  thus  brought  near  the  apex  of  the  medium  size  square.  Having 
selected  her  location,  the  female  takes  a  firm  hold  upon  the  sides  of 
the  square  and  completes  her  puncture  while  in  this  position.  It  may 
be  that  the  position  described  is  especially  favorable  for  obtaining  a 
firm  and  even  hold,  and  this  may  have  something  to  do  with  the  reg- 
ularity with  which  it  is  assumed.  If  so,  the  apparent  choice4  of  this 
location  for  the  puncture  is  only  partially  explained,  since  it  has  been 
often  shown  that  weevils  can  puncture  and  oviposit  successfully  in 
almost  any  portion  of  the  square  except  its  very  tip. 

Undoubtedly  there  are  other  reasons  than  those  of  mere  conven- 
ience which  have  so  impressed  themselves  upon  the  inherited  experi- 
ence of  the  weevils  as  to  lead  them  to  the  choice  of  this  position  and 
the  consequent  location  of  the  punctures  and  eggs.  Most  apparent 
of  these  reasons,  and  probably  also  most  important,  is  the  advantage 
which  this  location  affords  in  the  protection  of  the  egg  and  the  young 
larva  developing  from  it  against  the  attacks  of  natural  enemies  as 
well  as  from  the  injurious  effects  of  drying  and  decay. 

This  protection  is  readily  explained  by  several  facts.  The  place 
chosen  is  through  the  thickest  and  toughest  portion  of  the  floral 
envelopes  through  which  the  anthers  can  be  reached,  since  the  thick- 
est parts  of  Doth  calyx  and  corolla  are  toward  their  bases.  More 
21739— No.  45—04 5 


66 

important  than  the  thickness  of  the  layers  of  vegetable  matter  is  the 
character  of  the  tissues  through  which  the  puncture  passes.  Though 
corolla  and  calyx  are  both  modifications  of  original  leaf  tissue,  both 
have  changed  so  greatly  in  form  and  texture  that  the  resemblance  is 
recognized  only  by  those  somewhat  acquainted  with  plant  structure. 
The  corolla,  moreover,  has  changed  far  more  than  has  the  calyx,  and 
in  becoming  so  highly  specialized  its  tissue  has  lost  certain  powers 
still  retained  by  the  green  calyx  tissue.  The  particular  power  referred 
to  in  this  connection  is  the  ability  to  heal  small  wounds.  Punctures 
made  in  the  corolla  must,  therefore,  remain  open,  while  small  punc- 
tures through  the  calyx  will  in  most  cases  be  healed  by  the  natural 
outgrowth  of  the  tissue,  so  as  to  completely  fill  the  wounds  in  a  man- 
ner entirely  analogous  to  the  healing  of  wounds  in  the  bark  of  a  tree. 
The  custom  of  the  weevil  of  sealing  up  its  egg  punctures  with  a  mix- 
ture of  a  mucous  substance  and  excrement  is  of  great  advantage  and 
assistance  to  the  plant  in  the  healing  process.  While  undoubtedly 
applied  primarily  as  a  protection  to  the  egg,  it  serves  to  keep  the 
punctured  tissues  from  drying  and  decay,  and  thus  promotes  the 
process  of  repair. 

As  a  result  of  the  growth  thus  stimulated  in  the  calyx,  the  wound 
is  perfectly  healed  in  a  short  time,  and,  as  is  the  case  in  the  healing 
of  the  bark  of  trees,  here  also  we  find  a  corky  outgrowth  projecting 
above  the  general  surface  plane.  This  prominence  the  writer  has 
termed  a ' '  wart"  (PI.  X,  fig.  40).  The  healing  is  completed  even  before 
the  hatching  of  the  egg  takes  place,  and  thus  both  egg  and  larva  par- 
take of  the  benefit  of  its  protection. 

It  is  possible  for  the  puncture  to  heal  without  the  full  development 
of  the  wart,  and  it  is  also  possible  for  eggs  to  develop  successfully 
even  when  the  puncture  was  made  through  the  corolla  alone  and  no 
wart  developed,  but  in  the  latter  case  the  chances  are  rather  against 
it.  Occasionally  warts  do  develop  from  feeding  punctures  which 
were  small,  but  the  exact  conditions  under  which  this  takes  place 
have  not  been  determined. 

THE   ACT   OF   OVIPOSITION. 

The  general  process  of  making  punctures  has  been  described  pre- 
viously under  the  topic  of  "Food  habits"  (p.  38),  and  will  there- 
fore not  be  repeated  here.  Having  completed  the  formation  of  the 
egg  cavity,  the  female  withdraws  her  proboscis  and  turns  end  for 
end.  She  depresses  the  tip  of  her  abdomen  and  locates  therewith  the 
opening  to  the  cavity  by  feeling  or  scraping  around.  In  a  majority 
of  cases  the  opening  is  readily  found,  but  sometimes  it  is  not.  Then 
the  female  seems  often  to  lose  all  sense  of  locality,  but  continues 
scraping  with  the  tip  of  her  abdomen.  If  she  is  still  unsuccessful, 
she  turns  and  continues  the  search  by  means  of  the  antenna?,  just 


61 

.is  in  tin-  preliminary  examination  of  a  square  before  beginning  a 
puncture. 

In  many  oases  females  were  not  Iced  to  ad  aally  place  I  be  I  Lp  of  I  be 
proboscis  within  the  opening  of  the  cavitj  without  Beeming  to  be 
aware  of  its  proximity.  Wnen  the  cavitj  has  been  round  again  by 
the  antenna!  senses,  the  female  invariably  enlarges  it  before  turning 
again  to  inseri  the  ovipositor,  [f  the  search  with  the  antenna)  does 
not  prove  successful,  the  female  will  make  another  puncture  in  the 
same  manner  as  al  first,  appearing  to  know  that  no  egg  has  yet  been 
placed  in  thai  square. 

After  locating  the  cavity  by  the  tip  <>f  the  abdomen,  the  ovipositor 
is  first  protruded  to  the  bottom)  of  tlie  cavity,  in  which  it  appears  to 
be  firmly  held  in  position  by  the  two  terminal  papilla?  and  the  power 
of  enlarging  the  terminal  portion  of  the  ovipositor.  Slight  contrac- 
tions of  the  abdomen  occur  while  this  insertion  is  being  made.  In  a 
few  moments  much  stronger  contractions  maybe  seen,  and  often  a 
firmer  hold  is  taken  with  the  hind  legs  as  the  egg  is  passed  from  the 
body,  and  its  movement  may  be  seen  as  it  is  forced  along  within  the 
ovipositor  and  down  into  the  puncture.  Only  a  few  seconds  are 
required  to  complete  the  deposition  after  the  egg  enters  the  opening 
to  the  cavity.  The  ovipositor  is  then  withdrawn,  and  just  as  the  tip 
of  it  leaves  the  cavity  a  quantity  of  mucilaginous  material,  usually 
mixed  with  some  solid  excrement,  is  forced  into  the  opening  and 
smeared  around  over  the  same  by  means  of  the  tip  of  the  abdomen. 
This  seals  the  egg  puncture  and  the  act  of  oviposition  becomes  com- 
plete (PL  X,  fig.  39). 

TIME   REQUIRED   TO   DEPOSIT  AN   EGG. 

Observations  upon  this  point  were  very  conveniently  made  by  con- 
fining females  upon  squares  from  which  the  involucres  had  been 
removed.  A  plain  glass  cover  allowed  accurate  observations,  which 
were  made  to  the  fraction  of  a  minute.  The  time  required  to  com- 
plete the  excavation  and  the  time  required  to  place  the  egg  were  the 
two  points  especially  noted. 

The  time  of  making  the  puncture  was  noted  in  115  instances,  and 
this  was  found  to  average  5^  minutes.  The  time  varied  widely,  being 
from  1  to  13  minutes;  the  usual  range  was  from  4  to  8  minutes. 
From  the  time  that  the  weevil  began  to  puncture  till  the  sealing  of 
the  cavity  the  complete  act  of  oviposition  required  in  103  instances 
an  average  of  slightly  over  7^  minutes,  ranging  in  time  from  3  to  16 
minutes. 

As  these  observations  were  made  between  October  7  and  23,  the 
periods  given  may  be  slightly  longer  than  they  would  be  in  warmer 
weather.  However,  various  observations  made  in  the  field  in  mid- 
summer agree  very  closely  with  the  averages  given. 


68 

llkTE   OF   OVIPOSITION. 

Since  the  period  of  reproductive  activity  of  the  boll  weevil  is  so 
Long,  tin1  rate  at  which  eggs  are  deposited  is  a  question  requiring  much 
time  for  its  determination.  There  have  been  found  great  variations 
in  the  rate  at  different  seasons,  and  it  is  clear  that  oviposition  is  even 
more  strongly  influenced  by  variations  in  temperature  than  is  feeding. 
The  rate  sometimes  varies  unaccountably  and  very  abruptly  with  the 
same  female  upon  succeeding  days.  No  explanation  for  this  has  as 
yel  been  found.  The  rate  is  influenced  also  by  the  abundance  of 
chan  squares  which  the  weevil  can  find,  so  that  it  is  greater  in  the 
early  season,  as  the  degree  of  infestation  is  approaching  its  limit,  than 
after  infestation  has  reached  its  maximum. 

Two  extended  series  of  observations  have  been  made  to  determine 
especially  the  normal  average  and  the  maximum  ability  of  the  female. 

AVERAGE. 

Taking  first  54  females  which  had  gone  through  hibernation,  we 
find  that  they  deposited  on  the  average  2^  eggs  each  daily  in  the 
laboratory,  and  4  females  which  were  followed  under  field  conditions 
for  a  total  of  93  "  weevil-days  "  deposited  489  eggs  during  that  time,  or 
at  the  rate  of  5^  eggs  each  per  day.  Where  the  rate  of  activity  is  so 
great  it  is  probable  that  the  length  of  the  period  would  be  somewhat, 
but  not  proportionately,  shortened.  From  many  observations  made 
in  the  field  during  the  beginning  of  the  squaring  season  it  seems  prob- 
able that  a  rate  of  5  eggs  a  da}'  is  not  far  from  the  average  in  the  field. 

From  21  females  of  the  first  generation  a  laboratory  average  rate  of 
2^  eggs  each  daily  was  obtained.  Five  females  of  this  generation 
confined  in  a  cage  in  the  field  during  the  latter  part  of  August  for  a 
total  of  70  "  weevil  days"  deposited  an  average  of  64-  eggs  per  day. 
This  latter  rate  is  far  beyond  the  actual  average  rate  in  the  field  at 
that  period  because  of  the  fact  that  the  weevils  can  not  at  that  time 
find  enough  uninfested  squares  to  lead  them  to  deposit  so  many  eggs, 
but  the  possibility  remains  if  only  squares  enough  are  present. 

A  few  words  must  be  said  in  further  explanation  of  the  differences 
which  appear  between  the  field  and  laboratory  results.  In  the  case 
of  the  laboratory  figures  the  entire  oviposition  period  of  each  weevil 
and  the  entire  number  of  eggs  deposited  are  taken  into  the  account. 
As  there  is  a  gradual  increase  in  the  rate  of  production  of  eggs  after 
the  beginning  of  deposition  and  a  gradual  decrease  from  the  middle 
of  the  period  to  its  end,  the  general  average  is  much  lower  than  would 
be  that  taken  at  the  time  of  maximum  activity.  In  the  case  of  the 
field  figures  a  short  period  only  is  covered,  and  all  conditions  of  square 
supply  were  such  as  to  stimulate  the  weevil  to  its  greatest  possible 
activity. 


69 


M  \ \ I  Ml    M. 


The  daily  observations  made  upon  tie-  w<-<-\  ils  in  the  laboratory 
supph  a  vasl  Dumber  of  observations  from  which  to  select  maximum 
figures.  Ii  has  been  ^li<»\\n  thai  under  favorable  conditions  weevils 
ni;i\  !><■  expected  to  produce  an  average  of  ,;  eggs  .1  daj  for  .1  ennsid- 
erable  period  of  time.  Ii  is  aol  surprising,  therefore,  thai  some  of  I lie 
maximum  figures  obtained  are  very  much  larger  than  thai  number. 
A  iVw  instances  only  will  be  taken  from  among  thousands  of  daily 
records. 

The  highesl    record  of  eggs  deposited   shows  thai  -small  females 
deposited  together  L08  eggs  in  ;!  days,  or  al  the  daily  rate  of  18  i 
ra<h.     This  record  was  made  on  the  7th,  8th,  and  '.»ili  of  June,  L903. 

Table  XVII.     Maximum  rate  of  oviposition. 


Number   Days  in- 
of          eluded 
females,  inperiod. 

Number 

of 

females. 

Days  in- 
cluded 
inperiod. 

Total 
eggs  de- 
posited. 

Average 
per  day. 

T 

"> 

3 
5 
5 

1 
2 

108            is.  ii 
76           15.  a 

llMI               Kin 

11.0 

47             1 1 . s 

i 

1 

•> 
3 
5 

2 
3 

.-> 
2 

1 

4:< 
30 
114 
54 
12 

10.8 

10.11 
11.4 
9.0 

s.4 

12 

„; 

446            13.5 

13 

13 

283 

9.5 

STIMULATING   EFFECT   OF   ABUNDANCE    OF   SQUARES    [JPON    EGG 

DEPOSITION. 

Four  actively  laying  females  were  confined  together  upon  a  few 
squares  from  September  22  till  October  14,  1902,  and  during  this 
period  they  laid  a  total  of  227  eggs,  or  an  average  of  2.37  eggs  per 
weevil  per  day.  For  the  next  13  days  these  same  weevils  were  isolated 
and  supplied  with  an  abundance  of  squares.  During  this  shorter 
period  they  laid  2o<'>  eggs,  or  4.54  eggs  per  female  daily. 

Taking  equal  periods  as  near  together  as  possible  and  using  these 
same  weevils,  there  were  deposited  in  V-\  days  upon  a  few  squares 
1  1  1  eggs,  or  2.74  eggs  per  female  daily,  while  during  the  following  13 
days,  with  an  abundance  of  squares,  they  each  deposited  4.54 
a  day. 

These  figures  are  the  more  striking  because  the  stimulation  was 
plainly  shown  in  spite  of  the  general  tendency  to  lay  fewer  eggs  as  the 
weevils  grow  older  and  as  the  average  temperature  becomes  lower. 


RELATION   OF   WARTS   TO    OVIPOSITION. 

When    the   general    relation   of  the  warts  to  the   formation  of  egg 
punctures  was  first   recognized,  an   investigation  was  undertaken  to 

determine,  if  possible,  in  what  proportion  of  cases  the  warts  could  be 
1  raced  directly  to  egg  or  feeding  punctures.  For  this  purpose  a  large 
number  of  squares,  most  of  which  had  warts,  was  picked  from  plants 


70 

in  the  field  and  carefully  examined  in  the  laboratory.  Notes  were 
made  especially  upon  the  following  points:  The  number  of  warts,  the 
number  of  punctures  obviously  made  for  feeding  only,  the  number 
of  special  egg  punctures,  and  the  numbers  of  eggs,  larvae,  and  pupae 
found.  Only  those  excrescences  were  counted  as  warts  which  showed 
a  positive  elevation,  and,  as  was  expected,  many  eggs  were  found 
which  had  not  been  deposited  long  enough  for  a  wart  to  have  formed. 
Out  of  the  105  squares  examined,  20  showed  no  warts,  while  the 
remaining  79  squares  had  92  warts.  In  tracing  the  connection  of 
these  92  warts  it  was  found  that  77  at  least,  or  almost  84  per  cent  of 
the  total,  resulted  from  egg  punctures.  The  other  15  warts,  or  16  per 
cent,  were  assigned  to  feeding  punctures,  though  some  of  these  may 
possibly  have  been  egg  punctures  in  which  decay  had  concealed  all 
trace  of  the  eggs  or  small  larvae.  One-half  of  the  eggs  found  were 
in  punctures  closed  by  developed  warts,  and  it  is  likely  that  most  of 
the  other  half  were  of  too  recent  deposition  for  warts  to  have  formed. 
Three-fourths  of  the  larvae  found  in  this  lot  were  in  punctures  which 
had  been  overgrown  by  warts. 

In  another  series  of  35  older  squares,  38  warts  and  32  eggs,  larvae, 
and  pupae  were  found.  This  series  also  shows  that  at  least  84  per  cent 
of  the  warts  resulted  from  egg  punctures.  The  conclusion  seems  jus- 
tified, therefore,  that  warts  may  be  considered  as  the  most  conspicu- 
ous external  indication  of  the  presence  of  the  weevil  in  some  stage 
within  the  square. 

It  should  be  noted  in  connection  with  warts  that  feeding  frequently, 
and  oviposition  more  rarely,  is  followed  by  a  peculiar  gelatinization  of 
the  injured  portion  of  the  square.  This  condition  spreads,  and  the 
change  produces  a  considerable  internal  pressure,  so  that  the  square 
becomes  distorted  and  bulges,  especially  at  the  place  where  the  punc- 
ture was  made.  The  bulging  portion  often  resembles  somewhat  a 
wart  formation,  but  its  real  nature  is  very  different.  In  many  cases 
the  gelatinized  condition  appears  to  have  caused  the  death  of  the 
young  larvae,  either  by  the  pressure  or  by  the  abnormal  condition  of 
the  food  supply.  In  a  large  number  of  cases,  however,  this  condi- 
tion undoubtedly  results  from  what  were  feeding  injuries  only. 

EFFECTS   OF    OVIPOSITION   UPON   SQUARES. 

The  method  of  recording  the  progress  of  injury  to  each  square,  as 
was  done  in  the  field  cages,  has  furnished  much  data  upon  a  number 
of  important  points.  Among  these  the  two  of  most  importance  are, 
in  order  of  their  occurrence,  the  flaring  and  the  falling  of  the  square. 

FLARING. 

The  flaring  of  squares  (PL  X,  fig.  42)  is  one  of  the  most  apparent 
signs  of  weevil  presence,  although  by  no  means  an  invariable  accom- 
paniment, as  it  is  usually  thought  to  be.     Squares  flare  in  nearly  as 


71 

large  a  proportion  of  oases  from  adult  feeding  Injur}  alone  as  from 
Larval  injury  within.  \\\\  Injury  severe  enough  to  cause  the  falling 
of  the  square  is  as  Liable  to  cause  Raring  as  is  i  be  Lan  a  of  I  be  weeviL 
Flaring  results  from  an  unhealthy  condition,  whatever  ma}   be  the 

cause,  and  is  frequently  to  be  seen  in  squares  which  arc  about  i<>  be 
shed,  though  they  bave  never  been  injured  by  anj  insert.  Eowever, 
flaring  bas  come  to  be  popularly  associated  with  weevil  injury,  and 
must  therefore  1><'  quite  fully  considered. 

When  resulting  from  weevil  injury,  flaring  does  oot  begin,  asa  rule, 
immediately  after  the  injury,  but  only  within  from  one  to  three  days 
of  the  time  when  the  square  will  be  ready  to  fall.  In  especially 
severe  cases  of  feeding  injury,  paring  often  results  in  Less  than  twenty- 
four  hours.  Occasionally  the  growth  of  the  square  overcomes  the 
injury  from  feeding  and  the  involucre,  after  having  Mated,  again 
closes  up  and  the  square  continues  its  normal  development  as  though 
uninjured,  and  forms  a  perfect  boll.  More  frequently -the  square 
gradually  loses  its  healthy  green,  becoming  a  sickly  yellow  in  color, 
and  falls  in  a  short  time. 

When  injured  by  the  feeding  of  a  young  larva  as  the  direct  result 
of  successful  oviposit  ion,  flaring  has  been  found  in  an  average  of  J  30 
cases  to  bake  place  in  almost  exactly  7  days  from  the  deposition  of 
the  egg.  These  observations  cover  the  season  from  June  to  Septem- 
ber, when  the  developmental  period  averages  about  19  days.  Fully 
one-third  of  the  weevil's  full  development  has,  therefore,  taken  place 
before  flaring  results. 

FALLING. 

Squares  which  flare  because  of  injury  from  larval  feeding  within 
always  fall,  except  the  small  percentage  which,  though  entirely  cut 
off  from  all  vital  connection  with  the  plant,  still  remain  hanging 
thereon  by  a  small  strip  of  bark  and  gradually  become  dry  ami  brown 
upon  the  plant.  Falling  is  but  the  natural  final  consequence  of  injury 
or  disease  (PI.  XII,  fig.  46).  Whatever  its  cause,  it  is  brought 
about  in  exactly  the  same  way  as  the  shedding  of  leaves  by  the  plant 
in  the  fall,  by  the  formation  of  an  absciss  layer  of  corky  tissue  cutting 
off  the  fibro- vascular  bundles  supplying  nourishment  to  the  square. 
The  exact  location  of  the  cork  area  is  to  be  seen  at  the  scar  left  by 
every  fallen  square. 

In  539  cases  definitely  noted  between  June  and  September,  1003, 
the  average  lime  from  egg  deposition  to  the  falling  of  the  square  was 
9.6  days.  For  this  same  period  full  development  required  an  average 
of  19  days,  so  that  falling  occurred  at  the  middle  point  in  the  weevil's 
development.  From  a  comparison  of  the  time  of  flaring  with  that  of 
falling  it  is  seen  that  the  interval  between  these  two  points  averages 
about  2.5  days.  In  late  fall  the  time  between  oviposition  and  falling, 
as  recorded  in  21  cases,  wTas  found  to  be  about  10  days. 


72 

PERIOD    OF   OVIPOSITION. 

With  llir  exception  of  hibernated  weevils,  it  appears  that  oviposi- 
tion begins  with  most  females  within  a  week  after  they  begin  to  feed 
ami  continues  uninterruptedly  until  shortly  before  death.  While 
females  frequently  deposit  their  last  eggs  during  the  last  day  of  their 
life,  a  period  of  a  few  days  usually  intervenes  between  the  cessation 
<;l*  oviposit  ion  and  death. 

In  the  case  of  52  hibernated  females  the  actual  period  of  oviposition 
averaged  about  48  days,  the  maximum  being  fully  02  days. 

In  an  average  made  with  21  females  of  the  first  generation  the 
actual  period  was  almost  75  daj*s,  the  maximum  period  being  113  days. 

The  average  period  for  the  females  of  the  first  two  generations 
appears  to  be  longer  than  that  for  any  other.  In  the  third  generation 
the  average  period  for  11  females  was  58  days,  the  maximum  being  00 
days,  and  in  the  fifth  generation  for  5  females  the  period  averaged  48 
days,  with  the  maximum  only  02. 

The  approach  of  cold  weather  cuts  short  the  activity  of  the  weevils, 
which  become  adult  after  the  middle  of  August,  thereby  decreasing 
the  length  of  their  oviposition  period.  Weevils  which  pass  through 
the  winter  actually  live  longest,  but  as  it  must  take  more  or  less  vital- 
it}*  to  pass  through  the  long  hibernation  period  their  activity  in  the 
spring  is  thereby  lessened. 

The  weighted,  average  period  of  oviposition  of  the  80  females  here 
mentioned  is  55.0  da}*s. 

DOES   PARTHENOGENESIS    OCCUR? 

To  test  the  possibility  of  weevils  reproducing  parthenogenetically, 
12  individuals  were  isolated  from  the  very  beginning  of  their  adult 
life.  Each  beetle  was  supplied  daily  with  fresh,  clean  squares  and 
careful  watch  was  kept  for  eggs.  The  first  noticeable  point  was  that 
no  eggs  were  found  till  the  weevils  were  about  twice  as  old  as  females 
usually  are  when  they  deposit  their  first  eggs.  After  the}*  began  to 
oviposit,  it  was  found  that  a  very  small  proportion  of  the  eggs  were 
deposited  in  the  usual  manner  within  sealed  cavities  in  the  squares, 
but  nearly  all  of  them  had  been  left  on  the  surface,  usually  near  to 
the  opening  to  an  empty  egg  puncture.  This  same  habit  was  shown 
by  a  number  of  females,  and  so  can  not  be  ascribed  to  the  possible 
physical  weakness  of  the  individuals  tested.  The  number  of  eggs 
deposited  was  unusually  small,  and  those  few  placed  in  sealed  cavities 
failed  to  hatch.  After  somewhat  more  than  a  month  had  been  passed 
in  isolation,  one  pair  was  mated  to  see  if  .any  change  in  the  manner  of 
oviposition  would  result.  The  very  next  eggs  deposited  by  this  fer- 
tilized female  were  placed  in  the  square  and  the  cavity  sealed  up  in 
the  usual  maimer,  showing  that  her  infertile  condition  had  been  the 
cause  of  her  abnormal  manner  of  oviposition. 

A  much  more  extensive  series  of  experiments  along  this  line  is 
desirable  and  will  be  made. 


n 

DEVELOPMENT. 

PERCENTAGE    OF    WEEVILS    DEVELOPED    FROM    INFESTED 

SQUARES. 

During  the  season  of  L902  part  of  the  many  squares  gathered  in 
Infested  fields  for  the  breeding  of  weevils  were  followed  to  Learn  some- 
thing of  the  percentage  which  produced  normal  adults.  No  exami- 
nation was  made  for  those  nol  yielding  a  weevil.  The  decay  of  the 
square  during  the  period  from  its  falling  to  tin-  maximum  time  that 
must  be  allowed  for  weevils  to  escape  normally  so  obliterates  any 
small  amount  of  work  by  a  Larva  that  it  is  difficult  even  with  exami- 
nation t<>  determine  accurately  the  number  of  dead  small  Larvae. 

Table  XVIII. — Percentage  of  weevils  from  infested  squares. 


Locality. 

Approximate  dab  . 

Number 

of 
squares. 

Number 
weevils. 

Percenl 
age  ot 
squares 
producing 
weevils. 

Victoria,  Tex 

um. 

July  t<>  August 

1,125 

381 

334 
368 

360 

ins 

106 
365 
192 

33.0 

Victoria,  Tex 

1903. 
June 

82.0 

Do 

June  to  August 

August  to  September 

41.il 

Do.. 

52  '1 

Total. _._ 

3,087 

1,121 

:*>.  3 

It  seems  safe  to  conclude  that  throughout  the  season  fully  one-1  hird 
of  the  squares  which  fall  after  receiving  weevil  injury  may  be  expected 
to  produce  weevils. 

DEVELOPMENT  OF  WEEVILS  IN  SQUARES  WHICH  NEVER  FALL. 

It  is  generally  true  that  squares  seriously  injured  by  the  weevil 
sooner  or  later  fall  to  the  ground.  Some  plants,  however,  shed  the 
injured  squares  more  readily  than  do  others.  It  seems  to  he  a  mat- 
ter of  individual  variation  rather  than  a  varietal  character.  Thus 
occasional  plants  retain  a  large  proportion  of  their  infested  squares, 
which  hang  by  the  very  tip  of  the  base  of  the  stem.  Normally  the 
squares  are  shed  because  of  the  formation  of  an  absciss  layer  of  corky 
tissue  across  their  junction  with  the  stem.  In  the  ease  of  the  squares 
which  remain  hanging  the  formation  of  this  layer  seems  to  be  incom- 
plete, or  else  it  becomes  formed  in  an  unusual  plane,  so  thai  while  the 
square  is  effectualh'  cut  off,  it  merely  falls  over  and  hangs  by  a  bit  of 
bark  at  its  tip  (PI.  XII,  tig.  47).  In  this  position  it  dries  thoroughly 
and  becomes  of  a  dark-brown  color.  Plants  showing  6  or  8  of  these 
dried  brown  squares  are  quite  common  in  infested  fields.  Although 
exposed  to  complete  drying  and  the  direct  rays  of  the  sun,  the  larva' 
within  are  not  all  destroyed.  This  peculiarity  reminds  one  strongly 
of  the  European  Anthonomus  pomorum   the  work  of  which  in  cans- 


74 

ing  apple  buds  to  hang  dead  upon  the  trees  has  caused  the  common 
name  of  "Brenner"  to  be  applied  to  it. 

At  intervals  during  the  summer  of  1903  such  dried  squares  and 
small  dried  bolls  were  picked  for  careful  examination  in  the  labora- 
tory, the  condition  of  342  being  recorded,  with  the  following  results: 

Adults  present  2,  escaped  23;  pupse  alive  29,  dead  2;  larvae  alive  85, 
dead  47;  parasites  present  44,  escaped  6.  Sixty-three  squares  which 
failed  to  show  weevil  work  and  42  small  dried  bolls  from  which  the 
corollas  had  fallen  were  probably  destroyed  largely  by  the  feeding  of 
the  weevils.  Taking  the  total  number  of  squares  and  bolls  examined 
as  the  basis  of  computation,  it  appears  that  69.3  per  cent  of  them 
showed  weevils  present  in  some  stage.  Of  the  immature  stages,  30 
per  cent  were  dead,  14.6  per  cent  having  been  parasitized.  It  seems 
a  conservative  estimate  therefore  to  say  that  fully  one-third  of  these 
exposed  dried  squares  may  be  expected  to  produce  adults.  Consider- 
ing the  exposed  condition  of  such  squares  this  seems  to  be  a  very 
high  percentage. 

The  season  of  1903  was  not  as  hot  at  Victoria  as  was  that  of  1902, 
and  the  lower  temperature  prevailing  may  have  favored  the  develop- 
ment of  a  larger  proportion  of  the  weevils  in  these  squares  than  would 
normally  emerge.  The  maximum  temperature  reached  in  1902  was 
104.3°  F.,  while  in  1903  the  maximum  was  only  97.5°  F.  No  examina- 
tions of  this  subject  were  made  in  1902,  and  therefore  no  positive 
comparisons  can  be  drawn.  The  observations  made,  however,  cer- 
tainly show  that  a  complete  drying  of  the  square  does  not  necessarily 
destroy  the  larva,  and  that  a  square  may  undergo  far  more  exposure 
to  direct  sunshine  than  had  been  supposed  possible  without  causing 
the  death  of  the  larva  or  pupa  within. 

LENGTH  OF  THE  LIFE  CYCLE. 

This  question  has  been  studied  carefully,  both  in  the  laboratory 
and  in  the  field.  Most  of  the  observations  made  in  1902  were  in  the 
laboratory,  while  those  of  1903  were  in  the  field. 

In  the  laboratory  uninfested  squares  were  exposed  to  active  weevils 
for  oviposition,  and  the  supply  of  clean  squares  was  renewed  each 
day.  The  beginning  of  the  cycle  was  thus  known  to  within  a  few 
hours.  The  squares  with  eggs  were  carefully  kept  and  the  date  of 
emergence  of  each  adult  was  then  noted.  To  the  period  thus  found 
must  be  added  the  time  intervening  between  the  leaving  of  the  square 
and  the  deposition  of  the  first  eggs.  This  gives  the  length  of  the  life 
cycle.  The  material  upon  which  these  observations  were  made  was 
necessarily  other  than  that  used  in  determining  the  length  of  the 
various  stages.  The  period  in  bolls  is  far  different  from  that  in 
squares.     The  figures  here  given  refer  to  squares. 


T  u:i.i    XIX.     /.<  ngih  of  lift  oycl 


i  ibsen  al 

Time  in 
develo 

ieriod  of 

imiciit . 
Average. 

A\  nmgn  1  \mt 

Temporal  ore 

Period  covered. 

N  1 1  ii  i 

bar 

A. lull  to 

ovipo  i 

t  i  *  hi. 

Lenfth 

.,i 
cycle. 

A  rerage 

effort 

i\  e. 

Total 

A  i 

S«- 

MOB 
goal  in  to  September  :*> 
ttomber  16  to  <  October  18 
bober  >  bo  November  10 

90 

BOB 

08 

100 
LOO 

Day 

Hi  is 
18  85 
n  88 

l-  88 
L8  88 

Day*. 

S.  i 
17.B 

18. 8 
L9.0 

Day*. 

7.(1 
8.0 

:..  8 

Day 

[8  i 

-I    i 

84  0 

ii  0 

88.0 
88.1 

i 
904   i 

PJ 

ttO& 

•id.  first  generation: 

June  4  t.>  Jnly  r» 

August  80  to  September  88 

Total 

704  - 

m  i 

747 

10-2(5 

\Y 

17.8 

0.8 

84.0 

84.1 

-i-  I 

These  observations  eover  the  season  from  June  1  to  November  L6. 
Reproduction    undoubtedly  begins  somewhat  earlier  and  continues 

later  in  the  average  season  at  Victoria,  but  any  differences  which 
might  be  found  at  the  extremes  would  not  materially  affect  the  Loca- 
tion of  the  mean  in  so  large  a  series.  The  influence  of  varying  tem- 
perature during  the  same  period  but  in  different  seasons  is  clearly 
seen  by  a  comparison  of  the  figures  for  August  10  to  September  30, 
1902,  with  those  for  August  20  to  September  28,  1903.  The  period  for 
1902  was  exceptionally  warm,  as  shown  by  the  high  average  effective 
temperature,  while  in  1903  it  was  decidedly  cooler,  the  difference 
averaging  8°  F. ;  consequently  the  average  length  of  the  cjTcle  was 
fully  six  days  greater  in  1903  than  in  1902  at  the  same  period. 

Determinations  of  the  length  of  the  life  cycle  in  bolls  have  been 
made  in  only  a  few  instances.  In  7  cases  between  August  15  and 
November  11,  1903,  the  average  time  required  from  the  deposition  of 
the  egg  to  the  escape  of  the  adult  from  the  opening  boll  was  Gl  days. 
The  average  effective  temperature  for  the  period  was  31.7°  F.,  and 
the  average  total  effective  temperature  required  for  development  in 
bolls  was  therefore  1,933.7°  F.,  or  nearly  two  and  one-half  times  as 
much  as  in  squares.  Several  larvae  often  develop  within  a  single  boll 
(PI.  XI,  fig.  43).  They  appear  to  remain  in  the  larval  stage  until  the 
boll  becomes  sufficiently  mature  or  so  severely  injured  as  to  begin  to 
dry  and  crack  open.  When  this  condition  of  the  boll  is  reached,  pupa- 
tion takes  place,  and  by  the  time  the  spreading  of  the  carpels  is  suffi- 
cient to  permit  the  escape  of  the  weevils  they  have  become  adult. 

BROODS  OR  GENERATIONS. 


The  term  "brood"  can  hardly  be  applied  in  its  usual  sense  to  the 
generations  of  the  weevil,  as  was  pointed  out  by  Doctor  Howard  in 
the  first  circulars  of  the  Division  dealing  with  the  problem.  For  sev- 
eral reasons  no  line  of  distinction  can  be  drawn  between  the  genera- 
tions at  any  season  of  the  year,  not  even  between  hibernated  weevils 


76 

and  the  adults  of  the  lirsi  generation.  As  lias  been  shown,  Hie  aver- 
age period  of  oviposit  ion  among  hibernated  females  is  in  some  cases 
fully  ;>  months,  while  il  averages  48  days.  The  length  of  the  full 
life  cycle  for  the  lirsi  generation,  as  shown  in  Table  XIX,  is  24  days, 
and  as  the  time  for  the  second  generation  would  be  slightly  less,  it  is 
evident  that  the  first  eggs  for  the  third  generation  will  he  deposited 
at  the  same  time  as  those  for  the  middle  of  the  second  generation, 
and  also  with  the  very  last  of  the  eggs  deposited  by  hibernated 
females  for  the  first  generation.  The  great  overlapping  of  genera- 
tions thus  produced  prohibits  the  application  of  any  of  the  common 
methods  of  ascertaining  their  limits.  The  complexity  indicated  for 
the  first  three  generations  becomes  still  further  increased  as  the  season 
advances,  so  that  in  October,  for  example,  a  weevil  taken  in  the  field 
might  possibly  belong  to  any  one  of  six  generations.  Length  of  life 
and  the  period  of  reproductive  activity  are  important  factors  in  deter- 
mining the  average  number  of  generations.  Periods  of  greatest 
abundance  can  not  be  regarded  as  giving  any  reliable  information 
upon  this  point,  since  the  number  of  weevils  developed  soon  comes  to 
depend  largely  upon  the  suppl}7  of  squares. 

In  the  case  of  the  boll  weevil,  therefore,  the  information  upon  the 
number  of  generations  must  be  drawn  from  laboratory  sources.  Many 
of  the  hibernated  weevils  continue  to  deposit  eggs  until  the  middle  of 
'July,  and  some  are  active  for  fully  a  month  longer.  In  1903  the  last 
eggs  from  hibernated  weevils  were  deposited  on  August  27.  In  the 
course  of  breeding  experiments  made  in  1902  it  was  found  that  many 
weevils  which  had  become  adult  about  the  1st  of  August  would  con- 
tinue to  deposit  eggs  until  the  latter  part  of  November.  Considering 
the  longest-lived  weevils  and  their  last-laid  eggs,  therefore,  it  is  easily 
possible  for  two  generations  to  span  the  entire  year.  The  weevils 
developing  after  the  middle  of  November  may  go  into  hibernation, 
and  from  their  last-deposited  eggs  produce  weevils  whose  last  off- 
spring will  be  ready  for  successful  hibernation  again.  This  conclu- 
sion is  based  upon  actual  demonstration. 

The  maximum  number  of  generations  will  be  found  by  taking  the 
first,  instead  of  the  last,  deposited  eggs  in  each  case.  Rather  than  lay 
the  conclusions  open  to  question  by  taking  the  figures  found  for  occa- 
sional minimum  length  of  the  life  C37cle,  we  will  take  the  24-day 
period,  which  has  been  shown  to  be  the  average  between  June  4  and 
November  16.  Without  doubt  hibernated  females  begin  their  repro- 
ductive activity  in  average  seasons  by  Ma}7  1,  and  their  descendants 
continue  to  develop  normally  until  after  November  15.  Taking  the 
dates  mentioned,  however,  as  the  average  season  for  the  weevils,  we 
find  that  eight  generations,  each  having  the  average  period  of  devel- 
opment, may  usually  be  produced  within  the  year. 

In  determining  the  average  number  of  generations  one-third  the 
average  period  of  oviposition  should  be  added  to  the  average  life  C3Tcle 


for  each  generation."  As  it  has  been  found  that  the  average  poriod  of 
oviposition  is  about  5 1  days,  \n < *  must  allow  24  days  for  the  develop 
iiimi  of  ihr  average  adult  and  L8  more  days  for  the  female  t<»  deposit 
one  half  her  eggs.  Forty-two  days  is  therefore  about  the  average 
Length  of  a  generation;  and  we  ma}  thus  count  on  an  average  oi  about 
ftve  generations  between  May  l  and  December  I.  In  the  northern 
part  of  the  weevil  territory,  where  the  season  is  shorter  and  the  pre- 
vailing temperature  lower,  probably  only  four  generations  would  be 
(lc\  eloped. 

There  is  uo  basis  for  the  idea  that  there  is  a  distinct  hibernation 
brood.  I'll"  activity  of  the  adults  and  the  development  of  the  imma- 
ture stages  is  gradually  retarded  by  the  decline  in  temperature  until 
hibernation  lime  arrives.  Most  of  t  he  weevils  of  the  firsl  i \\<>  or  three 
generations  have  probably  died,  or  then  do  so,  while  most  of  the  ad  nils 
of  Later  generations,  having  si  ill  considerable  vitality,  will  go  into 
hibernation.  If  is  certain  that  every  generation  preceding  may  have 
some  direct  part  in  the  production  of  weevils  which  shall  hibernate. 
All  weevils  which  are  still  strong  and  healthy  when  cold  weather  comes 
on  may  he  expected  to  go  into  hibernation,  so  that  there  can  be  no 
special  brood  for  this  purpose. 

THERMAL  INFLUENCE  UPON  ACTIVITY  AND  DEVELOPMENT. 

The  influence  of  temperature  has  been  frequently  mentioned  as  an 
important  point,  but  it  may  be  more  clearly  understood  by  collecting 
some  of  the  most  important  observations  relating  to  it.  A  study  of 
this  subject  throws  much  light  upon  such  questions  as  seasonal  and 
daily  activity,  the  rapidity' of  development  at  various  seasons,  hiber- 
nation, and  the  time  of  emergence  from  hibernation.  The  influence 
upon  development  will  be  first  considered. 


«  One-third  is  nearer  the  correct  fraction  than  one-half,  since  it  hits  been  found 
thai  weevils  deposit  considerably  more  than  one-half  of  their  eggs  during  the  first 
half  of  their  oviposition  period. 


78 


Table  XX. — Thermal  influence  on  development. 


Stage. 


Egg- 
Larva 

Pupa . 


Entire   develop 
mental  period  . . 


Number 
of  obser- 
vations. 


KIT 
36 

196 

15 

15 

161 

81 

167 

29 

4 


305 
66 


100 

185 


Period. 


L902 

Sept.  4  to  Oct,  3 

Oct.  7  to  Nov.  13_... 
Nov.  24  to  Dec.  15... 

Sept,  6  to  Oct.  5 

Sept,  26  to  Oct. 21... 
Nov.  11  to  Dec.  12... 

July  6  to  31 

Sept,  15  to  Oct.  3 

Sept.  24  to  Oct.  28... 

Nov.  2tol3 

Dec.2to29 

Aug.  10  to  Sept.  30.. 
Sept.  16  to  Oct.  15... 
Oct.  8  to  Nov.  16.... 

1903 

June  4  to  July  15 

Aug.  20  to  Sept.  28.. 


Average 

time  for 

stage. 


Da  vs. 
3- 
4+ 
11.0 

7.5 

9.5 

25.0 

3. 5 
5.2 
6.0 
7.6 
14.5 

13.4 
17.5 
20.3 


18.3 
19.0 


Effective  tempera- 
ture. 


Average.     Total 


38.  G 
30. 0 

19.0 

35.7 
30.6 
19.5 

39.65 
36.0 
31.1 
26.2 

18.5 

41.0 
33.6 
29.5 


32.0 
33.1 


F. 

114.0 

126.0 

2«nu) 

267.7 
280.7 

487.5 

138.8 
187.2 
186.6 
199.1 
268.2 

549.4 

588.0 
598.8 


585.6 
628.9 


SUMMARY  OF  THE  PRECEDING  TABLE. 


Stage. 


Egg -- - 

Larva  

Pupa _ 

Total  development 

Observations  on  entire  period 


Total 
observa- 
tions. 


528 
225 
442 


1.195 
752 


Average  Average      Total 
period     effective  effective 
for       tempera-  tempera- 
stage,        ture  ture. 


3.75 

8.8 

5.1 


17.65 
17.7 


F. 
35.1 
34.3 
34.7 


34.8 
33.9 


F. 

141.6 
301.8 
177.0 


614.2 
600.0 


In  studying  the  influence  of  temperature  on  development  the  figures 
upon  the  separate  stages  serve  best,  as  they  give  the  widest  range.  In 
each  stage  it  may  be  seen  that  the  maximum  time  is  nearly,  if  not 
quite,  four  times  the  minimum,  while  the  average  effective  tempera- 
ture difference  is  in  the  inverse  order,  but  about  2  to  1.  In  com- 
paring the  minimum  and  maximum  total  effective  temperatures,  it 
appears  that  when  the  average  temperature  is  lowest  the  total  heat 
required  to  complete  the  development  of  the  stage  is  nearly  twice  as 
great  as  when  the  average  temperature  is  highest.  The  length  of  the 
developmental  period  is  therefore  not  exactly  inversely  proportional 
to  the  change  in  temperature.  The  retarding  influence  of  decreasing 
temperature  appears  to  affect  each  of  the  immature  stages  in  very 
nearly  the  same  degree.  The  total  effective  temperature  required 
forms  a  specific  constant,  which  is  fairly  uniform  for  average  effective 
temperatures  of  between  30°  and  40°  F.  These  temperatures  would, 
during  most  seasons,  prevail  from  June  to  October,  inclusive.  As  the 
average  effective  temperature  falls  below  25°  F.,  however,  there 
results  a  great  and  disproportionate  retardation  in  the  development. 
The  reason  for  this  difference  may  lie  in  the  fact  that  when  tempera- 


T9 

fore  is  ascending  from  32    r.  it    must  attain  .1   higher  point   bo  Btarl 
weevils  into  activity  than  that  .n   which  the  same  weevil  will  cease 
activity  when  the  mercury  is  going  down. 
The  observal  ions  upon  the  length  of  the  entire  developmental  period 

were  made  upon  a  different  Beries  of  ww\  iK  As  is  clearly  shown  in 
the  summary  given  in  the  Latter  pari  of  the  table,  the  sum  of  the 
average  lengths  of  the  three  stages  agrees  remarkably  closely  with 
the  length  of  tin*  entire  period  as  found  in  the  752  rases  observed. 
'Tins  close  agreement,  readied  by  entirely  different  methods,  indicates 
that  the  series  from  which  the  averages  are  obtained  are  sufficiently 
Large  to  give  constant  results,  and  therefore  thai  the  average  period 
of  development  throughout  the  season  of  weevil  activity  is  very  close 
to  Is  days. 

This  thermal  influence  upon  activity  in  feeding  and  oviposition  may 
be  shown  by  taking  various  lots  of  weevils  at  intervals  through  the 
season.  For  this  purpose  the  work  of  LO  males  and  LO  females  lias 
been  selected,  using  the  Laboratory  records  for  each  lot.  The  time 
covered  is  25  days  in  each  case  to  secure  a  fair  average,  and  25-day 
intervals  separate  the  lots  from  eaeli  other.  The  season  thus  covered 
begins  with  June  G  and  ends  with  November  28,  1903.  To  make  the 
comparison  fair,  average  conditions  as  to  sex,  age,  and  individual 
activity  must  be  established,  and  the  records  have  been  selected  with 
these  conditions  in  view. 


Table  XXI. — Thermal  influence  on  activity  in  feeding  and  ovipositing. 


Xum-   Number 

Period. 

Average 

Total. 

Daily  average     JEffgg*. 

berof      of  fe- 
males,    males. 

tempera- 
ture. 

Feeding 
punc- 
tures. 

Eggs. 

Feeding 
punc- 
tures. 

Eggs. 

Feeding 
pane-     Eggs, 
cores. 

Hi               in 
10               in 

in            id 
in            in 

1903. 

June  i»  to  :-fl>  -. 

July  25  to  A.ug.  l'.i 
Sept.  14  to  Oct.  8.... 
Nov.  ;J  to  27 

°  F. 
38. 1 
36.  5 
38.7 
84.6 

8,189 
8,325 

l.ran 
900 

794 

1,061 
669 
817 

87.6 
93.0 
61.6 
36.0 

31.8 

42.4 
2*>.4 

8.7 

4.4 
4.7 
3.1 
L.8 

3.2 

4.2 
2.6 
0.9 

The  average  number  of  daily  feeding  punctures  is  reckoned  for  both 
sexes  alike.  Though  the  females  made  more  than  half,  the  propor- 
tions can  not  be  positively  separated,  and  it  would  make  no  difference 
if  we  could  do  so.  It  is  noticeable  that  the  period  of  greatest  activity 
comes  in  midsummer,  With  the  first,  second,  and  third  generations 
actively  at  work.  Hibernated  weevils  working  in  June  show  greater 
activity  than  do  the  mixed  generations  which  occur  together  in  Septem- 
ber and  October,  though  the  temperature  does  not  greatly  vary.  In 
November,  with  a  marked  fall  in  temperature,  there  is  a  corresponding 
decrease  in  work,  but  especially  is  this  noticeable  in  egii;  deposition. 
It  appears  that  at  this  season  and  later  on  the  weevils  are  mostly  eat- 
ing to  live  until  it  becomes  cold  enough  for  them  to  hibernate, 


80 


LABORATORY  EXPERIMENT  IN  EFFECT  OF  TEMPERATURE  UPON 
LOCOMOTIVE  ACTIVITY. 

The  experiments  here  given  were  performed  by  Dr.  A.  W\  Morrill. 
In  the  absence  of  apparatus  especially  designed  for  such  work,  use 
was  made  of  a  very  simple  device,  constructed  as  follows: 

A  thermometer  was  passed  through  a  cork  and  inclosed  in  a  test 
tube,  which  in  turn  was  placed  within  a  hydrometer  cylinder  of  snl- 
Bcienl  depth  to  inclose  it  (PL  XIII,  fig.  49). 

Weevils  were  inclosed  in  the  test  tube  with  the  thermometer,  and 
the  temperature  of  the  cylinder  varied  either  by  heating  gently  or  by 
the  use  of  ice  water.  Starting  with  the  thermometer  at  04°  F.,  the  10 
weevils  inclosed  were  found  to  move  slowly,  half  of  them  being  quiet. 
As  the  temperature  was  gradually  raised  the  activity  of  the  weevils 
increased  up  to  105°  F.  When  the  temperature  reached  95°  F.,  or 
over,  the  weevils  were  running  up  and  down  the  tube.  By  filling  the 
cylinder  with  cold  water  the  temperature  was  lowered  to  86°  F..  a1 
which  point  the  weevils  began  to  cluster  at  the  top  on  the  cork  and 
were  crawling  slowly.  By  the  addition  of  ice  in  the  cylinder  the  tem- 
perature was  lowered  to  59°  F.,  at  which  point  5  weevils  were  sprawl- 
ing on  the  bottom  of  the  test  tube  or  clinging  to  one  another,  4  were 
clustered  on  the  stopper,  while  1  was  slowly  crawling  downward.  At 
50°  F.  6  weevils  at  the  bottom  showed  slight  signs  of  life  and  1  was 
crawling  slowly.  At  45.5°  F.  slight  signs  of  life  were  still  shown, 
while  at  40°  F.  occasional  movements  only  were  noted.  Upon  the  tem- 
perature being  raised  weevils  began  crawling  as  50°  F.  was  passed, 
and  at  64°  F.  all  had  left  the  bottom  and  were  crawling  upward. 
Some  recovered  much  more  quickly  than  did  others. 

The  temperature  was  again  lowered,  this  time  by  the  use  of  salt  with 
ice.  All  movement  ceased  at  37°  F.  The  cooling,  however,  was  con- 
tinued to  33°  F.,  after  which  it  was  slowly  raised  to  42°  F.,  at  which 
point  movements  began. 

In  a  general  way  these  results  agree  quite  closely  with  outdoor 
observations. 

HIBERNATION. 

Fven  after  frosts  have  blackened  the  foliage  and  squares  and 
entirely  checked  the  growth  of  the  plant,  some  weevils  can  be  found 
moving  in  a  cotton  field  upon  warm  days.  Weevils  which  are  old  and 
nearly  exhausted  die  as  the  cold  weather  comes  on.  Their  vitality 
has  been  expended  in  other  ways  and  they  do  not  survive  the  winter. 
Those  which  are  still  vigorous  and  strong  will  continue  to  feed  a  little, 
and  females  will  occasional^  deposit  eggs  so  long  as  cotton  remains 
green.  In  southern  Texas  larvre  and  pupa?  which  are  in  squares  when 
frost  comes  are  not  killed  thereb}7,  but  slowly  finish  their  development 
if  the  weather  is  warm  enough  for  any  activity,  and  the  young  adults 
thus  developed  may  live  the  winter  through  without  feeding.     As 


Plati    XIII. 


-iv 


Favorable  and  Unfan 


vBLE   UONDI 


for  Weevil  Acti 


Fig.  49,  Device  used  to  test  effect  of  temperature  upon  weevil  activity,  one-third  natural  size; 
fig.  50,  comparison  of  pilosity  on  "King"  (at  left)  and  "Mit  Afifi"  (at  right)  stems,  natural 
size:  Hlt.  51,  locality  found  very  favorable  to  hibernation  of  many  weevils.     (Original,  i 


XIV. 


£  vv>\ 


Insects  Often  Mistaken  for  Boll  Weevil. 

Fitrs.  52,  53,  Mexican  cotton  boll-weevil  (Antlionomus grandis),  much  enlarged  (redrawn,  after 
Hunter);  fig.  54,  Lixussp.,  enlarged  :>.;  times  (original);  fig.  55,  acorn  weevil  {Balaninus  uni- 
formU  auct.):  a,  female,  dorsal  view;  b,  same,  lateral  view:  c,  head,  snout,  and  antenna  of 
male— all  enlarged  J  times  (from  Chittenden,  unpublished);  fig.  56,  apple  curculio  (Cocco- 
torus  scuteUaris),  enlarged  (from  Insect  Life);  fig.  57,  plum  gouger  ( Anthonomus  prunicida), 
enlarged  (from  Insect  Life);  fig.  58,  Desmoris  scapalis,  enlarged  (original). 


81 

observed  i»\  Mr,  E.  A.  Schwarz  in  the  winter  of  L901  2,  weevils  may 
pass  the  winter  in  either  larval,  pupal,  or  adull  stages,  bnl  the  last 
earned  is  by  far  the  most  common  stage. 

Ii  is  likely  thai  a  large  part  of  the  weevils  found  in  the  squares  and 
bolls  during  the  first  pari  <>f  the  winter  will  be  in  the  Larval  stage, 
while,  owing  to  i  he  slow  development  which  takes  place,  a  larger  per- 
centage of  adults  will  be  found  toward  Bpring.  Mr.  J.  I).  Mitchell, 
of  Victoria,  Tex.,  took  a  number  of  live  larv®,  pupse,  and  adults  from 
bolls  in  a  Held  in  that  Locality  <>n  December  26,  L 903, after  "two  hard 
frosts  and  one  freeze."  Two  weeks  Later,  from  afield  al  the  same 
locality,  after  three  hard  frosts  and  two  freezes,  he  look  another  lol 
of  live  specimens  in  these  three  stages.  In  the  Latter  case  the  bolls 
examined  were  on  stalks  which  had  been  plowed  oul  two  weeks  before 
and  were  ready  for  burning  al  the  time  examined.  Mr.  Mitchell,  who 
is  an  excellent  and  reliable  observer,  writes:  kk()n  December 26,  there 
was  still  some  sap  in  the  cotton  stalks,"  and  on  January  10,  when  the 
second  examination  was  made,  "there  was  absolutely  none."  "The 
Larvae  seem  to  thrive  and  arrive  at  perfection  in  the  dead  and  dried 
bolls.  A  frost  or  freeze  at  :5<>  F.  does  not  hurt  the  larva'  or  pupae  in 
dead  bolls  in  the  field."  As  the  two  lots,  taken  together  with  four  others 
sent  January  17,  31,  and  February?  and  14, 1904,  include  197  specimens 
(23  larva1,  30  pupae,  and  144  adults)  it  is  evident  that  Large  numbers  of 
weevils  go  into  the  winter  in  the  immature  stages,  and  there  is  every 
probability  that,  in  the  southern  part  of  the  State  at  least,  many  of 
them  live  and  mature,  emerging  in  the  spring.  It  may  be  that  this 
gradual  maturity  of  the  hibernated  weevils  is  one  of  the  reasons  why 
they  emerge  so  irregularly  from  their  winter  quarters.  Not  all  wee- 
vils go  into  hibernation  at  the  same  time,  but  as  the  mean  average 
temperature  falls  to  between  55°and60°F.  they  gradually  cease  feed- 
ing, and,  numbed  and  sluggish,  they  crawl  into  almost  any  place 
which  furnishes  them  some  measure  of  protection  from  the  cold. 
Hibernating  weevils  are  therefore  to  be  found  in  many  situations  in 
the  field.  Where  the  cotton  stalks  are  allowed  to  stand  throughout 
the  winter  they  furnish  the  weevils  both  the  means  of  subsistence  late 
in  the  fall  and  an  abundance  of  favorable  hibernation  places  through- 
out the  field.  The  prospects  of  successful  hibernation  are  thereby 
multiplied  many  times;  and,  furthermore,  the  weevils  are  already 
distribut  d  over  the  field  when  they  first  become  act  ive  in  the  spring. 
The  grass  and  weeds  which  almost  invariably  abound  along  fence  lines 
are  exceedingly  favorable  to  the  successful  hibernation  of  many  wee- 
vils, so  that  it  will  be  found  generally  true  thai  the  worst  line' of 
infestation  in  the  spring  proceeds  from  the  outer  edges  of  the  field 
inward.  Where  cotton  and  corn  are  grown  in  adjacent  fields,  or 
where,  as  is  sometimes  the  case,  the  two  are  more  or  less  mixed  in 
the  same  held,  many  weevils  find  favorable  shelter  in  the  husks  and 
stalks  of  the  corn.  An  especially  favored  place  is  said  to  be  in  the 
2 1 7: 1! )— No.  45—04 0 


82 

longitudinal  groove  in  the  stalk  and  within  the  shelter  of  the  clasping 
base  of  the  leaf.  Perhaps  the  most  favorable  of  all  hibernating  con- 
ditions are  to  be  found  among  the  leaves  and  rubbish  abounding  in 
the  edges  of  timber  adjoining  cotton  fields.  From  such  places  the 
weevils  are  known  to  come  in  large  numbers  in  the  spring.  The 
timber  fringes  present  greater  difficulties  in  the  way  of  removing  the 
favorable  conditions  than  do  any  of  the  other  places  mentioned. 

Temperature  and  available  food  supply  seem  to  be  the  most  impor- 
tant factors  in  determining  the  time  of  hibernation.  In  general,  it 
may  be  said  that  many  weevils  are  active  so  long  as  their  food  con- 
tinues in  fit  condition  to  sustain  them.  Some,  however,  undoubtedly 
seek  shelter  before  frosts  occur.  From  numerous  observations  made 
in  the  laboratory,  it  appears  that  weevils  will  starve  when  deprived  of 
cotton  if  the  mean  average  temperature  continues  long  above  a  point 
somewhere  between  60°  and  65°  F.  As  the  mean  average  falls  below 
60°  hibernation  may  take  jilace  successful^. 

It  is  a  very  significant  fact  that  of  the  240  weevils  taken  from  the 
field  at  the  middle  of  December,  1902,  and  placed  in  hibernation,  38, 
or  15  8  per  cent,  passed  the  winter  successfully,  Avhile  of  the  116 
weevils  adult  before  November  15,  1903,  only  1,  or  less  than  1  per 
cent,  survived.  It  is  evident  that  the  weevils  which  pass  the  winter 
and  attack  the  crop  of  the  following  season  are  among  those  developed 
latest  in  the  fall  and  which,  in  consequence  of  that  fact,  have  not 
exhausted  their  vitalit}^  by  oviposition  or  any  considerable  length  of 
active  life. 

LENGTH  OF  HIBERNATION  PERIOD. 

As  the  observations  upon  this  point  have  all  been  made  at  Victoria, 
Tex.,  the  statements  made  refer  especially  to  that  locality.  It  must 
be  borne  in  mind  that  latitude  and  altitude,  as  well  as  seasonal  varia- 
tions, will  influence  the  limits  of  this  period.  In  general,  however,  it 
may  be  said  that  hibernation  begins  at  about  the  time  of  the  first 
hard  frost,  and  that  it  continues  until  the  mean  average  temperature 
has  been  for  some  time  above  60°  F.  Iri  the  spring  of  1903  weevils 
left  hibernation  quarters  at  Victoria  only  when  the  mean  average 
temperature  had  been  for  some  time  at  about  68°  F.  While  it  is  true 
that  weevils  if  disturbed  in  hibernation  are  active  at  much  lower 
temperatures  than  this,  for  some  reason  they  do  not  leave  the  shelter 
of  their  hibernation  places. 

At  Victoria,  Tex. ,  the  average  hibernation  season  may  be  said  to 
extend  from  about  December  1  to  about  April  1,  or  a  period  of  about 
1  months.  In  more  northern  latitudes  hibernation  will,  as  a  rule, 
begin  earlier  and  last  later,  covering  a  period  of  from  4  to  5  months, 


88 


APPARENTLY  FAVORABLE  CONDITIONS   FOR  HIBERNATION. 

In  December,  L902,  a  series  of  experiments  was  started  to  test  the 
influence  of  various  conditions  upon  the  successful  hibernation  of 
weevils.  Owing  bo  the  writer's  absence  from  Victoria  examinations 
could  not  be  made  al  intervals,  a>  would  have  been  desirable.  Bui 
,ii  the  middle  of  April,  L903,  careful  examinations  were  mad*'  to  ascer- 
tain tlif  Bhelter  in  whicb  live  weevils  were  found.  In  the  preparation 
of  hibernation  jars  several  inches  of  dirl  was  placed  al  the  bottom, 
and  above  t li.it  a  variety  of  such  rubbish  as  was  thought  might 
tempt  theweevilsto  Bhelter.  Dead  banana  leaves,  hay,  cotton  leaves, 
dry  bolls,  squares,  etc.,  were  among  the  things  used  as  rubbish.  As 
several  of  these  were  placed  in  each  jar  the  weevils  had  an  oppor- 
tunity to  choose  their  shelter.  Among  the  39  which  lived  through 
the  winter,  19  were  found  in  the  banana  Leaves,  7  in  hay,  5  in  dry 
cm  ion  leaves,  I  were  buried  in  dirt,  3  were  on  the  surface  of  the 
soil,  and  I  wa>  hiding  in  an  open  boll.  It  appears,  therefore,  that  31, 
o!  80  per  cent  of  the  39  live  weevils,  were  found  in  what  may  be 
termed  "leaf  rubbish."  It  was  noted  also  that  25  of  the  survivors 
passed  the  winter  out  of  doors  in  various  locations,  while  13  were 
under  shelter  indoors.  Of  the  weevils  placed  out  of  doors  all  but 
one  lot  were  protected  from  the  rain.  The  15  weevils  contained  in 
the  jar  which  became  wet  all  died,  while  but  few  of  the  jars  which 
were  dry  failed  to  show  a  live  weevil  in  the  spring.  Leaf  rubbish  and 
dryness  appear  to  be  favorable  factors  in  successful  hibernation. 

PERCENTAGE  OF  WEEVILS  HIBERNATING  SUCCESSFULLY. 

Naturally  the  percentage  of  weevils  living  through  the  winter  will 
depend  largely  upon  favorable  climatic  conditions  and  the  accessibil- 
ity of  suitable  shelter.  It  would  be  utterly  impossible  to  determine 
this  question  under  actual  outdoor  conditions,  and  our  inferences 
must  be  drawn  solely  from  percentages  found  to  survive  under  cage 
conditions.  In  the  laboratory  tests  referred  to  in  the  preceding  topic 
356  weevils  were  used.  Of  these,  240  were  brought  from  the  fields  at 
the  middle  of  December,  1902.  Among  these  weevils,  38,  or  15.8  per 
cent,  survived.  The  remaining  116  weevils  were  all  adult  after  Sep- 
tember 25,  1902,  and  had  been  kept  under  observation  in  the  labora- 
tory. ( )ne  single  weevil,  adult  November  12,  was  the  sole  survivor  of 
this  lot.  Since  the  weevils  brought  from  the  fields  in  the  middle  of 
December  would  be  a  correct  average  of  those  entering  hibernating 
conditions,  we  may  disregard  the  laboratory  specimens  in  drawing 
our  conclusions.  The  conditions  offered  would  seem  to  have  been 
favorable,  and  when  this  is  the  case  out  of  doors  it  appears  that  about 
one  in  six  of  weevils  found  in  the  field  at  hibernation  time  may  pass 
the  winter  successful^.  This  seems  a  very  high  percentage,  but 
when  we  consider  the  numbers  of  hibernating  weevils  often  occurring 


84 

upon  young  cotton  in  the  spring  it  seems  not  improbable  that  during 
favorable  seasons  something  like  this  percentage  of  the  weevils  find- 
ing favorable  shelter  will  live.  Of  course,  the  percentage  finding 
favorable  shelter  will  be  extremely  variable,  and  it  is  in  reducing  the 
number  and  accessibility  of  favorable  locations  that  the  cotton  planter 
has  one  of  his  very  best  opportunities  to  effect  the  destruction  of  a 
multitude  of  weevils,  and  thus  greatly  reduce  the  number  which  will 
emerge  from  hibernation  and  attack  the  crop  of  the  following  season. 
With  shelter  removed,  cold  and  changeable  weather  will  inevitably 
destroy  many,  and,  in  fact,  most,  of  the  weevils  which  would  other- 
wise survive. 

SEASONAL  HISTORY. 
EMERGENCE  FROM  HIBERNATION. 

Emergence  depends  largely,  as  has  been  already  shown,  upon  the 
mean  average  temperature  prevailing.  The  presence  of  food  does 
not  seem  to  affect  it.  In  the  season  of  1903  for  one  month  preceding 
the  emergence  of  weevils  at  Victoria  the  mean  average  temperature 
was  65.4°  F.  For  the  first  two  weeks  of  April  it  averaged  68.4°  F. 
Weevils  left  their  winter  quarters  from  the  middle  to  the  last  of 
April.  While  the  mean  average  temperature  for  May  was  nearly  o~ 
lower  than  the  temperature  prevailing  at  the  time  of  emergence, 
weevils  remained  actively  at  work  in  the  fields.  In  the  fall  also 
weevils  remained  at  work  at  a  lower  temperature  than  that  which 
seems  to  be  necessary  to  draw  them  from  their  winter  quarters.  The 
reason  for  this  fact  is  not  apparent,  but  it  is  certain  that  once  having 
left  hibernation  weevils  will  remain  active  at  considerably  lower  tem- 
peratures. If  the  temperature  becomes  too  low  they  remain  quiet 
without  taking  food  for  long  periods  of  time.  If  taken  from  their 
winter  quarters  weevils  will  be  found  active  at  ordinary  day  tempera- 
tures long  before  they  would  normally  venture  from  their  hiding 
places  of  their  own  accord.  Weevils  thus  removed  have  been  kept 
for  a  month  without  food  or  water,  and  they  then  assumed  their 
normal  activities  when  food  was  supplied  to  them. 

After  considerable  search  at  San  Diego  in  the  spring  of  1895,  on 
April  -7  Mr.  Schwarz  found  the  first  specimens  working  upon  seppa 
plants  from  roots  which  were  then  2- years  old.  As  the  weevils  first 
appeared  in  that  locality  in  August,  1894,  the  number  of  hibernat- 
ing weevils  could  not  have  been  as  great  as  in  succeeding  years, 
and  consequently  in  the  spring  of  1895  hibernated  specimens  were 
"exceedingly  rare."  At  Victoria,  Tex.,  in  the  spring  of  1902,  Mr. 
Schwarz  found  the  first  Aveevils  working  upon  volunteer  plants  on  April 
15.  In  the  same  locality  the  writer  found,  in  1903,  that  weevils  left 
their  winter  quarters  between  April  10  and  May  1.  Evidence  was 
found  indicating  that  in  some  fields  they  began  to  move  as  early  as 
March  28.     At  Calvert,  Tex.,  also  in  1903,  Mr.  Harris  found  the  first 


weevils  working  on  cotton  on  April  L2.      At  Victoria,  in  L904,  weevils 
\N«it'  found  in  numbers  apon  seppa  plants  <>n  March  11  and  they 
were  found  moving  in  the  Held  ai  intervals  throughoul  the  winter. 
From  these  observations  it  appears  that  normal  emergence  takes 

place   usually  some  lime  in  April,  whether  the  first  Or  the  last  of  the 

month  depending  largely  upon  the  earliness  of  the  season.     Further- 
more, the  emergence  of  the  first  weevils  may  lake  place  from  two  to 

four  weeks   before  that    of   the   last.       In  this    fact   lies  one   of   the  two 

great  obstacles  which  prevent  the  successful  application  of  poisons 
to  the  early  cotton  as  a  means  of  (lest  roying  the  weevils.    The  second 

obstacle  Is  explained  on  pages  41-43. 

Owing  to  the  empty  condition  of  the  alimentary  canal,  hibernated 
weevils  are  able  to  fly  with  ease,  and  this  they  must  do  in  their  search 

for  food.      Doubtless  many  perish  soon  after  emergence,  even  if  they 
find  food  which  many  others  never  succeed  in  reaching. 

APPARENT  DEPENDENCE  OF  REPRODUCTION  UPON  FOOD 
03TAINED  FROM  SQUARES. 

During  the  fall  of  1002  a  series  of  experiments,  lasting  for  12  weeks, 
was  made  to  determine  the  length  of  life  of  weevils  fed  solely  upon 
leaves.  In  one  lot,  consisting  of  9  males  and  8  females,  the  average 
length  of  life  of  the  females  was  25  days,  while  that  of  the  males  was 
30  days.  Though  this  period  far  exceeded  the  normal  time  usually 
passed  between  the  emergence  of  adults  and  the  beginning  of  egg 
deposition,  no  eggs  were  found.  Dissection  of  the  females  which 
lived  Longest  showed  that  their  ovaries  were  still  in  latent  condi- 
tion, though  the  weevils  were  then  81  days  old.  Few  instances  of 
copulation  were  observed  among  weevils  fed  upon  leaves  alone,  and 
among  nearly  70  weevils  which  were  thus  tested,  no  eggs  were  ever 
deposited.  After  a  period  of  3  weeks  upon  leaves,  11  weevils  were 
transferred  to  squares.  Females  in  this  lot  began  to  lay  in  4  days, 
and  4  of  them  deposited  323  eggs  in  an  average  time  of  20  days.  The 
conclusion  seems  plain  that  so  long  as  leaves  alone  are  fed  upon 
eggs  do  not  develop,  while  a  diet  of  squares  leads  to  the  development 
of  eggs  in  about  4  days.  It  is  worthy  of  note  that  the  interval 
between  t he  first  feeding  upon  squares  and  the  deposition  of  the  first 
eggs  is  almost  the  same  with  these  weevils  taken  in  middle  life  as 
with  weevils  which  have  just  emerged. 

An  examination  of  hibernated  females  taken  in  the  spring  of  1903, 
whicli  had  fed  for  G  weeks  upon  cotton  leaves,  showed  that  their 
ovaries  were  still  latent.  Copulation  was  rarely  observed  among 
hibernated  weevils  until  after  squares  had  been  given  them.  In  a  few 
days  after  feeding  upon  squares,  mating  and  oviposition  began.  The 
average  period  was  from  3  to  5  days,  and  having  once  begun,  ovipo- 
sition continued  regularly. 

It  has  been  found  that  food  passes  the  alimentary  canal  in  less  than 


86 

24  hours.  Assimilation,  therefore,  must  he  very  rapid.  It  is  evident 
that  while  leaves  will  sustain  life  certain  nutritive  elements  found 
only  in  squares  are  essential  in  the  production  of  eggs. 

Upon  dissecting  weevils  just  taken  from  hibernation  it  was  found 
that  females  contained  no  developed  eggs,  but  that  their  ovaries  were 
in  an  inactive  condition,  similar  to  those  of  females  which  had  fed  for 
months  entirely  upon  leaves  during  the  previous  fall.  Upon  examin- 
ing females  taken  from  seppa  cotton  later  in  the  spring,  but  before 
squares  had  appeared,  it  was  found  that  they  also  were  in  similar 
condition.  This  was  also  true  of  females  kept  in  the  laboratory  from 
the  time  of  emergence  from  hibernation  until  squares  became  abund- 
ant, with  only  leaves  for  food.  It  seems  peculiar  that  upon  a  purely 
leaf  diet  eggs  are  not  developed,  but  all  observations  made  indicate 
that  this  is  the  case.  It  can  not  be  said  definitely  whether  the  females 
examined  had  been  fertilized,  but  it  is  certain  that  they  were  not 
ready  to  deposit  eggs. 

PROGRESS  OF  INFESTATION  IN  FIELDS. 

From  among  the  many  notes  made  upon  this  point  the  results  of 
the  study  of  two  fields  are  here  p resented.  The  first  field,  consisting 
of  about  15  acres,  had  been  planted  in  cotton  for  several  years  and 
was  closely  surrounded  by  other  cotton  fields.  The  second  field  of 
35  acres  was  upon  newly  broken  land  and  situated  in  a  comparatively 
isolated  location. 

Examinations  were  made  frequently  to  determine  approximately  the 
percentage  of  infested  squares  present  in  various  parts  of  these  fields. 
The  conditions  of  the  examinations  were  made  as  uniform  as  was 
possible.  The  fields  were  divided  into  blocks,  and  practically  the 
same  ground  was  covered  in  each  block  upon  succeeding  examinations. 

Table  XXII. — Progress  of  infestation,  field  1. 


Block. 

Date. 

Number 

of 
squares 
exam- 
ined. 

Number 

of 
squares 
infested. 

Percent- 
age. 

Remarks. 

1903. 
(June  8,  9 

4,200 
467 
249 
278 
91 
358 
331 
300 
699 

675 
211 
193 
224 
85 
168 
148 
100 
636 

16.0 
45.0 
77.5 
80.6 
93.5 
46.6 
44.7 
33.3 
91.1 

Work  of  hibernated  weevils  only. 
Second  generation  at  work. 
Third  generation  beginning. 

July  13     . 

I 

Uuly  22 

August  4 

About  four  generations  now  working. 
Much  cotton  dying  from  root  rot. 

(July  30 

II 

1  August  1 

1  August  4 

[August  20 

Total 

6,973 

2,440 

35.0 

The  observations  made  in  Block  I  cover  a  longer  period,  and  are, 
therefore,  more  suggestive  than  those  made  in  Block  II.  Evidently 
infestation  began  with  the  first  appearance  of  squares.  So  long  as 
the  hibernated  weevils  alone  were  at  work  the  percentage  did  not 
increase  very  rapidly,  but  with  the  advent  of  the  second  generation 


-7 

a  much  larger  proportion  of  the  squares  became  infested.  (  orre 
Bponding  increases  are  seen  with  the  third  generation,  inn  from  that 
time  on  so  large  a  proportion  <>f  the  squares  was  Infested  thai  the 
percentage  did  not  increase  bo  rapidly.  It  may  be  noted  in  each 
block  that  the  maximum  percentage  of  infestation  is  slightly  over  90. 
Some  clean  squares  ma\  always  be  found,  however  numerous  the 
weevils  may  be,  bul  those  which  escape  weevil  puncture  are  mostly 
less  than  half  gro¥  a,  ><>  thai  while  the  percentage  varies  bu1  slight  ly, 
i(>u  of  these  clean  squares  would  escape  the  later  attacks  of  the 
weevils  and  form  blooms.  In  Block  I  the  infestation  was  quite  gen- 
eral. The  situation  of  the  block  was  especially  favorable  to  the 
hibernation  of  a  Large  number  of  weevils.  Bounded  on  one  side  by  a 
fence  row,  on  the  opposite  side  by  a  cornfield,  and  at  one  end  by  I  lie 
buildings  used  by  the  tenant,  an  abundance  of  hibernating  places  was 

afforded  the  weevils,  and  as  a  result  they  came  into  the  field  in  the 
spring  from  all  those  directions  (PI.  XIII,  fig.  51).  It  was  noticeable, 
however,  that  the  portion  of  greatest  infestation  early  in  the  season 
lay  in  the  corner  between  the  fence  row  and  the  buildings.     From  the 

feme  row  especially  the  weevils  spread  toward  the  center  of  the  field. 
The  second  field,  as  has  been  slated,  was  comparatively  isolated,  so 
that  infestation  first  began  late  in  the  season.  Block  I  in  this  case 
lay  in  the  corner  between  cross-roads.  Block  II  adjoined  the  road 
farther  on,  while  the  third  block  was  taken  as  far  from  these  two  as 
was  possible.  Infestation  began  in  the  corner  covered  by  Block  I. 
In  studying  this  block,  lots  1,  2,  and  3,  as  numbered  in  the  table,  were 
taken  diagonally  across  the  block,  away  from  the  corner.  Block  II 
was  separated  from  Block  I  by  corn,  the  ends  of  the  rows  being  at 
the  road  which  passed  the  point  of  original  infestation.  The  lots  in 
Block  II  were  taken  in  their  order  at  varying  distances  from  the  road. 
Block  III  was  some  distance  from  the  others.  In  this  case  lot  1  was 
taken  along  the  edge  on  the  side  toward  the  other  blocks,  while  lot  2 
was  taken  in  the  middle  of  the  block. 

Table  XXIII. — Progress  of  infestation,  field  2. 


Block 

Lot. 

Date. 

Number 

of 
squares 

exam- 
ined. 

Number 

of 
squares 
infested. 

Percent- 
age of 

infesta- 
tion. 

Remarks. 

1903. 

fAUgUSt  t) 

885 
414 
210 
800 
362 
L85 
180 
80S 
138 
150 
800 
818 
859 
166 
330 

15 
351 

18 

0 
841 

i>2 
156 

31 
105 

9 
130 

20.0 

1 

2  1 

[August  22 

^  \    j-Lot  2,  iu  middle  of  Block  I. 

I 

August  (> 

: 

2 

3 

1 

[....do 

0.0    (Lot  3,  opposite  corner  of    block 
66  t>   j     from  lot  1. 

\  August  22 

:<:{.:>    (Lot  1,  near  public  road,  passing 
86  7    I     lot  1  of  Block  1 

IL 

(August  13. 

1  August  24  __ 

15.3 

77  2 

[August  13. 

6  0 

[August  84.. 

('.:.  n 

[August  17 

91            41.7     Edge  of  block. 
888            88  0 

n~L 

|  August  2M 

August  17 

:>s            :.':'  9     Middle  of  block 

[August  89 

890 

88 

From  a  study  of  Block  I  it  is  evident  that  infestation  began  some 
time  in  July,  since  when  first  found  it  was  entirely  restricted  to  a 
small  area.  A  study  of  each  block  chronologically  shows  the  steady 
but  rapid  progress  of  the  weevil,  as  does  also  a  comparison  of  the 
three  blocks  at  the  nearest  possible  dates.  The  tremendous  activity 
of  weevils  in  midsummer  and  the  possible  rapidity  of  their  spread  is 
clearly  shown  in  this  field. 

A  study  of  two  other  fields  yielded  practically  similar  results.  The 
dates  of  examinations,  with  the  percentages  found  in  each  case,  will 
be  given.  In  field  3  there  was  found,  upon  June  2,  3  per  cent  of  infes- 
tation; on  July  16,  25.9  per  cent;  on  August  15,  65.9  per  cent.  This 
field  was  from  native  seed  and  was  planted  about  three  weeks  earlier 
than  field  4,  which  was  of  King  seed,  and  just  across  a  turn  row  from 
field  3.  In  field  4  infestation  began  very  late,  as  on  August  8  there 
appeared  to  be  only  2  per  cent  and  on  August  15,  23.6  per  cent,  while 
on  August  26  it  had  increased  to  91.5  per  cent,  which  is  about  the 
usual  percentage  of  maximum  infestation. 

Under  the  conditions  usually  prevailing  cotton  will  cease  to  make 
when  about  two-thirds  of  the  squares  have  become  infested,  since  the 
weevils  have  then  become  sufficiently  numerous  to  attack  nearly  all 
of  the  remaining  clean  squares  before  they  have  time  to  bloom  and 
form  bolls.  Even  bolls  which  have  set  before  this  percentage  of 
infestation  is  reached  are  not  entirely  safe,  as  the  smallest  ones  will 
be  more  readily  attacked  by  weevils,  as  they  have  greater  difficulty 
in  finding  uninfested  squares. 

WEEVIL   INJURY  vs.   SQUARE    PRODUCTION. 

At  the  beginning  of  infestation  the  indications  of  the  weevil's  pres- 
ence are  inconspicuous.  Even  wdien  considerably  advanced  most 
farmers  do  not  recognize  the  injury,  and  thus  are  led  to  believe  that 
the  insect  has  not  appeared.  Among  the  most  conspicuous  indica- 
tions of  the  weevil's  presence  may  be  mentioned  the  falling  of  infested 
squares.  As  the  squares  remain  on  the  plant  after  they  become 
infested  fully  as  long  as  they  lie  upon  the  ground  between  the  time 
of  their  falling  and  the  emergence  of  the  weevil,  it  is  plain  that  less 
than  half  of  the  actually  infested  squares  will  ordinarily  be  observed. 
Previous  to  falling  infested  squares  gradually  turn  yellow,  and  in 
most  cases  flare  somewhat;  but  flaring  is  by  no  means  as  closely  related 
to  weevil  injury  as  might  be  supposed.  As  the  percentage  of  infesta- 
tion increases  the  great  numbers  of  squares  on  the  ground  must  attract 
attention  (PL  XII,  fig.  46).  Shedding  of  squares  may  take  place  for 
other  reasons  than  the  attack  of  the  weevil,  but  in  fair  weather,  when 
large  numbers  of  squares  are  found  upon  the  ground,  the  weevil  is 
probably  present.  As  infestation  approaches  its  climax  there  is  a 
great  decrease  in  the  number  of  blooms,  and  when  a  field  is  found  at 
blooming  age  with  many  squares,  but  no  blooms,  the  weevils  are 


B9 

almost  certainly  abundant.  The  conditions  named  form  the  most 
conspicuous  indications  of  practically  total  infestation.  Daring  tin* 
season  of  L903  ii  was  found  thai  a  condition  <>f  total  infestation  was 
reached  some  time  between  August  I  and  20  in  most  fields  within  the 
infested  area.  This  condition  is,  as  a  pule,  coincident  with  the  appear- 
ance  in  large  numbers  of  weevils  of  the  fourth  generation.  The  exact 
time  will  varj  in  different  seasons,  and  even  in  adjacent  infested  lie  Ms, 
because  of  \  arying  condil  ions. 

No!  only  is  the  maximum  number  of  weevils  present  in  the  field  in 
midsummer,  but  their  capacity  for  injury  is  also  greatest  at  that 
time.  Practically  all  of  the  crop  that  will  be  made  must  have  been 
set  before  this  time.     After  this  bolls  will  form  only  by  accident. 

A  large  scries  of  examinations  made  by  Messrs.  Harris  and  Morrill 
at  Calvert,  Tex.,  shows  the  very  rapid  increase  in  the  percentage  of 
infested  squares  which  usually  takes  place  a  few  weeks  earlier  than 
it  did  in  L903.  'The  figures  given  in  each  column  in  the  table  show- 
also  the  closeness  with  which  the  weevil  activity  kept  pace  with  the 
formation  of  squares  after  the  period  of  maximum  infestation  had 
once  been  reached.  The  general  influence  of  climatic  conditions  may 
be  seen  by  a  comparison  of  the  last-  two  columns  in  t  he  table,  but  t  his 
point  would  be  much  more  clearly  shown  by  a  series  of  examinations 
made  during  the  first  half  of  the  growing  season,  at  which  time  tem- 
perature and  moisture  would  have  greatest  influence  upon  weevil 
development  and  injury.  One  hundred  squares  were  picked  promis- 
cuously in  each  block  for  the  determination  of  the  percentages  given 
in  the  columns  for  these  34  blocks,  thus  making  a  total  of  17,000 
squares  examined. 

Table  XXIV. — Study  of  the  infestation  of  cotton  fields  at  Calvert,  Tex. 


Time  of  record. 

Block. 

1 

2 

3 

4 

5 

6 

1 

8 

9 

Hi 

11 

IS 

20 

21 

22 

1903. 

A  u  urn -t  15-17 

72 

'.if, 
93 
92 
94 

68 
91 

'Jl 
si 
93 

64 
96 

92 
89 

91) 

65 

1(K) 
91 
91 
90 

71 
96 
9't 

97 
91 

63 

;•; 

94 
98 
98 

66 
98 
93 

91 
88 

v,s 
98 
92 
89 
83 

59 

90 
95 
89 
92 

60 
87 
98 

91 

99 

59 
90 

94 
94 

96 

60 
88 
96 
96 

94 

4(i 
98 
88 
95 

95 

4t> 
95 
89 
94 
93 

55 

September  2  i        

S9 

'HI 

'11 

( October  22  :.'4 

Ml 

Time  of  record. 

Block. 

23 

24 

25 

26 

27 

27  a 

28 

29 

30 

81 

32 

:$:5 

50 

51 

52 

Looa 

August  !•">  17 

4S 
09 
92 
1)4 
96 

50 
94 
91 
94 
91 

54 
91 
98 

91) 
89 

47 
91 
94 
96 

98 

49 
B8 
93 

9:5 

N 

58 
93 

98 
94 
91 

54 

95 
90 
92 

97 

58 
91 
96 
98 

'.hi 

:.i 
91 
94 
95 

54 
93 

96 
99 
95 

57 
93 
93 
94 
97 

55 
W 

91 

96 
93 

62 

89 
9:5 
92 
96 

66 

94 

92 

87 
97 

58 

September  2-4    . 

% 

September  14-17 

95 

October  1   :> 

86 

October  22-24 

97 

90 


Table  XXIV.   -Study  of  the  infestation  of  cotton  fields  at  Calvert,  Tex.— Cont'd. 


Block. 

Average 

infesta- 
tion for 
entire  34 
blocks. 

Time  of  record. 

:»:! 

54        55 

;.<> 

Climatic  conditions. 

August  15-17 

September  2-4 

September  U-17.. . 

October  1-3,. 

October  22-24 

(14 

89 
91 
78 
95 

69 

94 

96 
92 
99 

67 

90 
97 

88 

98 

62 

97 
95 
89 
95 

/'<<<;, it. 

58.88 

91.41 

93.21) 

<u..v, 

93.67 

Rainfall  in  July.  1903.  8.61  inches  (or  nearly 

four  times  normal  rainfall »:   Aug.  1  to  15, 

nearly  normal  rainfall  (0.79inch,  Aug.  2). 

Average  temperature,  July,  85°  F.;   Aug. 

1  to  15.  85J°  F. 

Rainfall  from  Aug.  15  to  Sept.  2,  0.9  inch 
(nearly  normal).  Average  temperature, 
same  period.  84i°  F. 

Rainfall  from  Sept.  2  to  14,  0.8  inch  (about 
one-half  normal; .  Average  temperature. 
83*°  F. 

Rainfall  from  Sept.  14  to  Oct.  1.  0.14  inch 
(about  one-tenth  normal) .  Average  tem- 
perature, 76?°  F. 

Rainfall  from  Oct.  1  to  22.  3.63  inches  (more 
than  two  times  normal).  Average  tem- 
perature, 74°  F. 

Still  another  series  of  observations  made  by  Doctor  Morrill,  at  Austin, 
Tex.,  shows  that  similar  conditions  prevailed  in  localities  nearly  100 
miles  apart.  For  each  of  these  percentages  300  squares  were  exam- 
ined, thus  making  14,400  observations  in  the  series. 

Table  XXV. — Study  of  the  infestation  of  cotton  fields  at  Austin,  Tex. 


Time  of  record. 

Block. 

1           2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

1903. 
August  4-7 

29.0     34.0 
95. 3     95.0 
90. 3     88.0 

11.0 
95.3 
90.3 

15.0 
96.7 
90.0 

10.0 
92.7 
94.7 

9.0 
87.3 
a5.3 

19.0 
95.0 
92.0 

33.0 

!'ti.  7 
92.  0 

43.0 
96.7 
96.0 

43. 0 
96.7 
96.0 

36.0 
95.3 
92.7 

31.0 

September  7-9 

October  5-7 

93.7 
96.0 

Block. 

Average 
infesta- 
tion, en- 
tire 16 
blocks. 

Time  of  record. 

13 

14 

15 

16 

Climatic  conditions. 

1903. 
August  4-7 

33.0 
93.7 
92.0 

36.0 
98.0 
89.3 

49.0 
98.3 
92.7 

55.0 
97.7 
92.7 

Per  cent. 
30.37 

95.25 

91.87 

Julv  rainfall,  12.65  inches  (above  nor- 

September 7-9 

October  5-7 

mal  10  35  inches).  Mean  average 
temperature.  July.  82.6°  F. 

August  rainfall.  0.79  inch  (below 
normal  1.64  inch).  Mean  average 
temperature.  82.6°  F. 

September  rainfall,  trace  i  below  nor- 
mal 3.72  inches  i.  Mean  average 
temperature.  76°  F. 

As  the  first  records  at  Austin  were  made  about  ten  days  earlier 
than  were  those  at  Calvert,  the}'  serve  to  show  a  much  greater  total 
increase  in  the  average  infestation  during  August,  though  the  average 
daily  increase  in  the  percentage  of  infestation  agrees  very  closely  in 
the  two  localities,  being  1.8  per  cent  at  Calvert  and  1.9  per  cent  at 
Austin. 

A  decrease  in  square  production  accompanies  the  maturity  of  the 
bulk  of  the  crop,  owing  to  the  fact  that  the  assimilative  power  of  the 


91 

plant  is  largely  consumed  in  maturing  seed.  Dry  weather  normally 
occurring  at  thi>  period  also  causes  a  decrease  in  the  number  of 
weevils  present.  Not  only  are  there  Less  squares  to  become  infested, 
inn  each  square  is  also  subjected  to  greater  injur} .  and  many  which 
would  otherwise  have  produced  weevils  are  unfitted  as  food  for  the 
larvae  by  the  decay  which  follows  the  numerous  punctures.  Several 
eggs  may  be  deposited  in  one  square,  bu1  as  a  rule  only  one  weevil 
will  result.  At  this  season  weevils  turn  their  attention  to  young  bolls 
upon  which  the  injury  previous  to  ihis  time  has  been  comparatively 
slight.  It  was  found  in  one  ease  iliat  •'!•'»  or  l<>  percent  of  the  bolls 
were  infested,  while  l  .">  percent  of  the  squares  were  yet  clean.  The 
Longer  period  of  development  required  by  larva*  in  bolls  also  serves  to 
decrease  the  number  of  weevils  produced.  While  the  actual  number 
of  weevils  begins  1<>  decrease  within  a  short  time  after  the  period  of 
maximum  infestation  is  reached,  the  apparent  numbers  may  possibly 
be  greater.  The  decreased  number  of  squares  serves  to  concentrate 
the  weevils  upon  those  remaining,  and  therefore  the  number  of  weevils 
found  in  any  square  will  be  so  much  the  greater. 

RELATION   OF   WEEVILS   TO    "TOP    CROP." 

The  hope  of  gathering  a  top  crop  is  the  "  will-o'-thc-wisp"  of  cotton 
planters.  After  considerable  cotton  lias  been  matured  fall  rains  often 
stimulate  the  production  of  a  large  number  of  squares,  and  many 
planters  arc  misled  by  the  hope  of  gathering  a  large  top  crop  from 
this  growth.  The  joints  of  the  plant  are  short,  and  the  squares  are 
formed  rapidly  and  near  together.  Though  weevils  may  have  been 
exceedingly  numerous  in  the  field,  their  numbers  will  have  become  so 
decreased  in  the  manner  described  under  the  preceding  heading  that 
they  can  rarely  keep  up  with  the  production  of  squares  at  this  period 
of  rapid  growth.  Many  blooms  may  appear,  and  the  hope  of  a  large 
top  crop  increases. 

The  fact,  however,  as  stated  by  prominent  growers,  is  that  before 
the  appearance  of  the  weevil  they  actually  gathered  only  about  three 
top  crops  in  25  years.  The  chance  of  its  development,  though  always 
small,  becomes  hopeless  wherever  the  weevil  is  present  in  consider- 
able numbers.  (See  Tables  XXIII,  XXIV,  and  XXV,  and  average  of 
infestation  of  entire  fields,  p.  8S.)  Neither  the  hopelessness  of  gath- 
ering a  top  crop  nor  the  actual  injury  which  is  being  done  to  the  crop 
of  the  succeeding  year  by  allowing  that  growth  to  continue  until 
frost  kills  it  is  generally  appreciated  by  planters.  Because  of  the 
apparent  abundance  of  squares  and  the  presence  of  many  blooms  the 
plants  are  allowed  to  stand  long  after  they  might  otherwise  have  been 
destroyed.  As  is  the  case  in  the  early  spring,  however,  the  abun- 
dance of  squares  increases  greatly  the  production  of  weevils;  and 
though  a  few  bolls  may  set.  they  are  almost  certain  to  become  infested 
before  they  reach  maturity.     Every  condition,  therefore,  contributes 


92 

to  the  production  of  an  immense  number  of  weevils  very  late  in  the 
season  and  at  just  the  right  lime  for  their  successful  hibernation. 
As  the  result  of  this,  far  greater  injury  is  done  to  the  crop  of  the 
following  season,  with  a  comparatively  small  gain  in  the  yield  of  the 
present  season.  Furthermore,  plants  standing  until  frosts  kill  them 
are  often  allowed  to  stand  throughout  the  remainder  of  the  winter, 
and  these  furnish  an  abundance  of  favorable  hibernating  places  for 
the  weevils.  The  consequence  of  this  practice  is  that  so  many  weevils 
are  carried  through  the  winter  alive  that  the  yield  of  the  next  year 
will  be  much  less  than  what  it  might  have  been  but  for  the  farmer's 
indulgence  of  the  forlorn  hope  of  a  top  crop. 

From  these  considerations  it  seems  plain  that  within  the  weevil  ter- 
ritory all  hope  of  a  top  crop  must  be  given  up  and  the  destruction  of 
the  stalks  be  practiced  as  early  in  the  fall  as  may  be  possible.  This 
practice  is  one  of  the  essential  elements  in  the  successful  control  of 
the  weevil. 

SOME    REASONS   FOR   EARLY  DESTRUCTION   OF   STALKS. 

It  is  naturally  impossible  to  fix  any  date  for  the  destruction  of  stalks 
which  would  apply  to  all  localities  and  under  all  conditions.  The 
condition  of  the  soil  must  be  considered  as  well  as  that  of  the  maturity 
of  the  crop.  While  the  condition  of  the  soil  can  not  be  changed,  the 
time  of  the  maturity  of  the  crop  is  largely  within  the  control  of  the 
planter,  since  by  early  planting  of  early  maturing  varieties  nearly 
the  entire  yield  may  be  matured  before  the  usual  time  of  picking  of 
the  first  cotton  from  native  seed.  Whatever  the  qualifications  which 
must  be  made,  the}^  do  not  decrease  the  general  strength  of  the  reasons 
which  may  be  given  for  the  early  destruction  of  stalks.  The  principal 
reasons  are  three  in  number: 

First,  the  absolute  prevention  of  development  of  a  multitude  of 
weevils  which  would  become  adult  within  a  few  weeks  of  hibernation 
time.  The  destruction  of  the  immature  stages  of  weevils  already 
present  in  infested  squares  is  surely  accomplished,  while  the  further 
growth  of  squares  which  may  become  later  infested  is  also  prevented. 
This  stops  immediately  the  development  of  weevils  which  would  nor- 
maUy  hibernate  successfully,  and  by  decreasing  the  number  of  wee- 
vils which  will  emerge  in  the  spring  the  chances  of  a  good  crop  for 
the  following  season  are  greatly  increased. 

The  second  reason  is  that  by  a  proper  manipulation  of  the  stalks 
a  very  great  majority  of  the  weevils  which  are  already  adult  can  be 
destroyed.  One  of  the  most  successful  practices  is  to  throw  the  stalks 
in  windrows,  and  as  soon  as  they  have  become  sufficient^  dry  they 
may  be  burned.  If  the  weather  is  favorable,  the  burning  may  take 
place  in  about  two  weeks,  and  many  of  the  weevils  will  not  have  left 
the  cotton  stalks  by  that  time.  In  case  rains  delay  the  drying  it  will 
be  found  advantageous  to  expedite  burning  by  the  use  of  crude  petro- 


98 

learn.  Grazing  the  fields  with  cattle,  as  some  have  recommended, 
will  destroy  much  of  the  growth  and  prevent  further  development  of 
weevils,  but  M  allows  enough  <>f  foliage  i<>  remain  to  Bustain  th<'  life 
of  many  which  are  already  adult  until  it  becomes  sufficiently  cold  for 
them  to  hibernate.  Not  only  does  burning  destroy  most  of  the  wee- 
vils, but  it  also  destroys  the  shelter  which  might  be  afforded  the  few 
thai  would  escape,  and  the  chances  of  successful  hibernation  are 
largely  decreased  by  this  practice. 

The  third  reason  may  be  found  In  the  fact  that  the  clearing  of  the 
ground  renders  possible  a  deep  fall  plowing.  This  catches  such  wee- 
vils as  might  still  be  in  squares  on  the  ground.  The  ground  becomes 
clean  by  this  practice,  so  that  no  vestige  of  the  food  plant  remains, 

and  living  weevils,  if  by  any  possibility  they  have  escaped  thus  far, 
must  either  starve  or.  perish  from  exposure.  Furthermore,  fall  plow- 
big  places  the  ground  in  the  best  possible  condition  and  makes  it 
ready  for  immediate  working  as  early  as  planting  may  begin  in  the 
spring,  thereby  saving  delay  in  the  starting  of  the  crop.  As  stalks 
must  be  destroyed  in  some  way  before  the  field  can  be  replanted,  the 
practices  here  mentioned  will  not  add  greatly  to  the  cost  of  dest  ruc- 
tion. Even  if  some  cotton  is  present  upon  the  stalks  at  the  time  of 
their  destruction,  this  small  item  is  hardly  worthy  of  consideration  in 
comparison  with  the  greatly  increased  crop  and  the  more  early  matur- 
ing and  better  quality  of  staple  which  may  be  obtained  by  the  adop- 
tion of  this  recommendation. 

Having  studied  carefully  the  methods  of  weevil  control  which 
have  heretofore  been  recommended,  the  writers  firmly  believe  that 
the  destruction  of  the  stalks  in  the  early  fall  is  the  most  effective  method 
known  of  actually  reducing  the  numbers  of  the  weevil.  Early  destruc- 
tion will  cost  but  a  small  fraction  of  the  expense  necessary  to  the  fre- 
quent picking  up  of  the  squares  infested  by  hibernated  weevils  in  the 
spring,  and  is  far  more  thorough  as  a  means  of  reducing  the  numbers 
of  the  weevil  than  is  the  practice  of  picking  hibernated  weevils  from 
the  young  plants. 

Early  dest  ruction  of  the  stalks  is  essential  to  the  greatest  success  of 
any  system  of  controlling  this  pest.  All  other  practices  recom- 
mended— early  planting  of  early  maturing  varieties,  thorough  culti- 
vation, fertilization,  etc.  (see  p.  112) — though  very  valuable  in  securing 
the  crop,  are  perhaps  of  greatest  value  because  they  prepare  the  way 
for  this  early  destruction  which  so  reduces  the  actual  number  of  wee- 
vils hibernating  successfully  that  the  other  recommendations  may 
yield  their  best  results.  Since  t  he  earliest  investigations  made  by  this 
Division  upon  the  boll  weevil,  it  has  been  recognized  that  this  prac- 
tice is  of  the  first  importance,  and  the  experience  of  recent  years  has 
but  added  certainty  to  this  conviction.  Planters  have,  however,  been 
slow  to  change  their  methods  of  cultivation,  but  enough  have  adopted 
the  recommendation  to  prove  its  efficiency.     It  must  not  be  thought 


94 

that  the  procuring  of  the  immediate  crop  is  the  only  desideratum. 
Early  and  complete  destruction  of  stalks  is  undoubtedly  the  most 
important  single  element  insuring  success  for  the  subsequent  year. 

DISSEMINATION. 

Two  principal  periods  of  dissemination  may  be  found  during  a  sea- 
son. The  first  is  when  the  hibernated  weevils  leave  their  winter 
quarters  and  go  in  search  of  food.  Having  found  food,  the  spread  is 
mainly  controlled  by  the  limitation  of  the  food  supply.  So  long  as 
an  abundance  of  growing  tips  or  of  clean  squares  is  near  at  hand 
weevils  will  not  travel  far,  but  when  the  condition  of  total  infestation 
is  reached  the  period  of  greatest  dissemination  is  also  attained. 

In  any  given  field  dissemination  takes  place  mainly  by  the  short 
flights  and  crawling  of  the  weevils.  The  search  of  the  female  for  unin- 
fested  squares  is  the  principal  factor  in  their  movement.  Heavy 
winds  seem  to  be  of  comparatively  small  importance,  as  weevils  do 
not  take  flight  readily  at  such  times;  but  light,  warm  breezes,  such  as 
prevail  throughout  the  coast  country  of  Texas,  undoubtedly  tend  to 
carry  them  in  a  general  northerly  direction,  and  the  continuous  equi- 
noctial storms  of  the  fall  in  Texas,  occurring  at  the  very  time  the 
pests  are  most  active,  have  undoubtedly  had  a  strong  effect  in  the 
same  direction. 

The  two  principal  lines  of  spread  will  be  found  along  railways  and 
water  courses.  Between  localities  separated  by  short  distances,  traffic 
along  highways  is  probably  the  chief  factor.  The  distance  which  a 
weevil  may  travel  in  flight  has  never  been  determined,  but  from  a 
study  of  their  habits  of  flight  it  would  seem  to  be  comparatively  short. 
Floods  and  the  motion  of  water  along  water  courses  frequently  serve 
to  distribute  many  weevils  along  the  edge  of  high- water  mark.  As 
river  valleys  are  largely  devoted  to  cotton  culture,  this  would  seem  to 
be  no  small  factor  in  the  transportation  of  the  weevils. 

Over  longer  distances  the  usual  means  of  commercial  traffic  must 
be  held  responsible.  Shipments  of  cotton,  whether  for  ginning  or  in 
baled  condition,  are  likely  to  carry  many  weevils.  Shipments  of  seed 
for  planting,  coming  from  infested  localities,  are  almost  certain  to 
carry  weevils,  and  shipments  of  seed  to  oil  mills  may  also  assist  in 
scattering  them.  The  pests  are  often  carried  far  outside  of  infested 
regions  in  the  shipment  of  seed  to  northern  oil  mills.  From  the  mills 
they  are  carried  to  the  farms  in  the  hulls  or  other  by-products  used 
for  feeding  cattle.  Many  of  the  isolated  colonies  in  northern  Texas 
originated  in  this  manner. 

WEEVILS  IN  SEED  HOUSES  AT  GINNERIES. 

Careful  observations  made  by  Mr.  Schwarz  at  Victoria  throughout 
the  winter  of  1901-2  revealed  great  numbers  of  weevils  about  the  gins. 
They  occurred  especially  in  the  seed  houses,  and  the  danger  of  the 


transportation  <>f  the  pests  from  one  Locality  i<»  another  was  most 
evident . 

A.  casual  examination  of  the  dirt  separators  which  are  qo^  Id  use 
in  the  more  modern  ginneries  shows  that  immense  numbers  of  wreevils 
brought  in  from  the  fields  are  separated  from  the  Lint  by  these  devices. 
Even  where  these  separators  are  used,  however,  a  short  search  in  tin- 
seed  house  will  shom  that  many  weevils  pass  through  alive.  A  single 
hour's  search  in  the  Bced  house  of  a  first-class  ginnery,  where  dirt 
separators  are  in  use,  yielded  seven  boll  weevils  in  perfect  condition, 
and  a  number  of  other  and  much  Larger  insects.  In  addition  t<>  these 
a  number  of  fairly  Large  spiders,  most  of  which  were  in  perfect  condi- 
tion, were  also  found.  Numerous  pupa'  may  pass  through  the  gins 
unharmed  in  the  cells  formed  by  the  larva*.  These  cells  are  similar, 
both  in  size  and  shape,  to  the  seed,  and  may  often  be  mistaken  Ihere- 
for  (PI.  XI.,  fig.  44).  Distribution  of  weevils  in  seed  is  therefore 
easily  possible,  and  nninfested  localities  should  guard  carefully 
against  importing  weevils  in  this  way. 

The  most  valuable  suggestion  for  reducing  the  important  effect 
that  gins  have  in  spreading  the  weevil  is  in  the  improvement  of  the 
cleaning  devices  referred  to  above,  and  in  encouraging -their  more 
general  use.  A  particular  study  of  this  matter  will  be  made  during 
tin-  season  of  1U04. 

NATURAL  CONTROL. 

Doubtless  many  factors  are  concerned  in  the  natural  control  of  the 
boll  weevil.  The  most  important  ones  are  probably  included  among 
the  following  topics: 

MECHANICAL  CONTROL. 

PILOSE   OBSTACLES   TO   WEEVIL   PROGRESS. 

In  testing  the  susceptibility  of  various  cottons  to  weevil  injury  it 
was  found  that  the  variety  of  Egyptian  cotton  grown  (Mit  Afifi)  was 
more  severely  injured  than  was  any  other.  The  next  in  order  were 
Sea  Island  and  Cuban  tree  cotton,  while  the  American  cottons,  repre- 
sented especially  by  King's  Improved,  were  less  severely  injured  than 
were  any  of  the  others.  It  may  be  noted  that  the  three  varieties  first 
mentioned  seem  more  closely  related  to  each  other  than  any  of  them 
do  to  the  American.  The  reason  for  the  evident  choice  of  these  cot- 
tmis  was  carefully  sought  for,  but  the  only  difference  which  seemed 
worthy  of  consideration  was  found  in  the  varying  degree  of  pilosity 
upon  the  stems  (PI.  XIII,  fig.  50).  It  was  found  that  Egyptian  stems 
were  almost  perfectly  smooth,  while  Sea  Island  and  Cuban  resembled 
it  closely  in  that  respect.  Many  American  cottons,  and  King's 
Improved  especially,  are  quite  pilose,  and  it  was  often  noted  that  upon 
these  weevils  showed  some  slight  difficulty  in  moving  about  or  in 
climbing  the  pilose  stems  of  the  plant.     While  this  obstacle  to  weevil 


96 

activity  may  seem  slight  to  account  for  the  evident  selection  of  the 
smoother  varieties,  no  greater  difference  could  be  found.  As  is  shown 
by  Table  XI,  on  page  46,  the  selection  is  not  due  to  a  difference  in  tasti 
of  i  in'  squares. 

Tn  order  to  test  the  resistance  which  varying  degrees  of  pilosity 
might  offer  to  weevil  progress,  a  number  of  experiments  were  mad'1 
with  various  stems  or  fruits.  In  climbing  upon  the  stems  of  Kin- 
plants  weevils  would  catch  the  spines  with  the  forefeet  while  pushing 
themselves  upward  by  means  of  the  tibial  spurs  of  the  hind  Legs 
placed  against  the  epidermis  and  between  the  spines.  It  was  evidem 
that  their  progress  was  considerably  hindered,  and  several  attempts 
were  often  made  before  a  firm  foothold  was  secured. 

Okra  pods  were  next  tried,  as  upon  them  the  spines  are  very  short 
and  stiff.     Weevils  climbed  these  pods  with  little  difficulty. 

The  seed  pods  of  Sunset  Hibiscus  were  also  tested.  The  spines 
upon  these  are  from  2  to  3  millimeters  long;  they  stand  thickly  and 
are  quite  stiff.  Over  these  spines  weevils  walked  easily,  but  though 
they  attempted  vigorously  to  get  their  heads  down  between  the  spines 
far  enough  to  feed,  they  were  unable  to  do  so.  A  number  of  weevils 
were  kept -for  several  dajTs  upon  these  pods,  but  they  were  unable  to 
feed.  The  spines  were  then  removed  from  a  small  area,  and  the 
insects  began  to  feed  immediately. 

Weevils  travel  with  difficulty  over  loose  cotton  fibers,  as  their  feet 
become  entangled  among  them. 

DESTRUCTION     OF    LARVJB    AND    PUP.E    IN    BOLLS    AND    SQUARES    BY 
ABNORMAL   PLANT   GROWTH. 

In  making  examination  of  several  thousands  of  infested  squares  a 
small  percentage  was  found  in  which  the  larvae  had  evidently  been 
killed  by  an  abnormal  condition  of  the  interior,  which  may  be  char- 
acterized as  a  process  of  gelatinization.  This  change  begins  at  the 
point  of  injury  and  spreads.  Instead  of  the  normal  growth  of  the 
anthers  there  takes  place  a  change  which  appears  to  be  something  like 
the  swelling  of  starch  granules.  The  interior  becomes  soft  and  pulpy, 
and  by  the  swelling  considerable  internal  pressure  is  prod  need.  The 
death  of  the  larva?  results  either  from  unfavorable  food  conditions  or 
from  the  internal  pressure,  which  in  many  cases  is  sufficient  to  distort 
the  square.  Whether  from  these  or  other  causes,  from  10  to  20  per 
cent  of  the  larvae  usually  die  within  the  squares. 

Gelatinization  sometimes  occurs  in  small  bolls,  but  more  rarely  as 
bolls  become  larger  and  more  mature.  In  large  bolls  in  which  seeds 
are  nearly  matured  the  feeding  of  the  weevil  larvae  often  causes  seeds 
to  sprout,  and  in  several  such  cases  pupa?  have  been  found  crushed 
by  the  rapid  growth  of  the  caiilicle. 

In  examining  nearly  1,000  bolls,  taken  partly  from  King  and  partly 
from  native  cotton,  it  was  found  that  in  the  early  maturing  King  the 


Pla-       • 


\IS> 


59 


61 


^-r^ 


SF' 


/^, 


w 


Insects  Often  Mistaken  for  the  Boll  Weevil. 

Figs.  59,  60,  Transverse  Bans  i  Barfs  ti<insr,r.<<i  i.  much  enlarged  (original  i;  fig.  61,  Oentrinus  peni- 
eellw,  enlarged  (original  i:  riir.  62,  coffee-bean  weevil  i  Araect  rus  fasdculotus):  a,  larva:  b,  beetle; 
•  ■.  pupa,  enlarged  (from  Chittenden);  figs.  63,  64,  Chalcodermus  smeus,  enlarged  from  Chitten- 
den i. 


Bui.  4". 


XVI. 


1 ;  -¥f 


Insects  Often  Mistaken  for  the  Boll  Weevil. 

Figs.  65,  66,  Sharpshooter  [HomaZodisea  triquetra),  enlarged  from  Insect  Life);  fig.  67,  cotton 
stainei  (Dysdereus  suturellus),  enlarged  (from  [nsecl  Life);  fig.  68,  cotton  stalk  borer  [Ataxia 
crypto),  enlarged  (from  Howard);  tig.  69,  imbricated  snout  beetle  [Epicaerus  iwJbricaius), 
enlarged  (from  Chittenden);  fig.  70.  snapping  beetle  [Monocrepidius  vespertinus),  enlarged 
(from  Chittenden  i. 


97 

rcontage  of  larvw  and  pupn  killed  was  much  Larger  than  In  the 
In  native  cotton  about  20  per  <-<"nt  <>f  the  larvas  wrere  found 
to  be  dead,  w  l> i l<-  In  the  King  U.2  per  cent  were  dead.     In  all  proba- 
bility the  more  rapid  M<>\n  of  Bap  in  the  early  developing  King  cotton 
largel)  responsible  for  the  changes  which  led  to  the  death  of  the 

CLIMATIC    CONTROL. 

[iNFLl   ENCE  OF   *  LDfATIG  CONDITIONS    UPON   WEEVIL    MULTIPLICATION 

\\D   i\.iii;v. 

Three  principal  factors  affect  the  development,  spread,  and  dest  ruc- 
tivenesa  of  the  boll  weevil— temperature,  precipitation,  and  food  sup- 
ply. So  perfectly  has  the  weevil  become  adapted  to  Its  single  food 
plant  that  it  is  a  very  not  Iceable  tact  thai  the  climatic  condil  ions  which 
are  most  favorable  to  the  growth  of  the  plant  are  most  favorable  also 
for  the  normal  activities  and  development  of  the  weevil.  Affecting 
one  in  the  same  direct  ion  as  the  other,  the  pest  is,  therefore,  enabled  to 
very  closely  keep  pace  with  its  food  supply  under  all  kinds  of  natural 
condil  ions! 

The  most  favorable  conditions  for  the  weevil  area  high  tempera- 
ture and  abundant  moisture  throughout  along  season.  These  con- 
ditions favor  the  growth  of  the  plant  and  produce  a  very  large 
number  of  squares,  which  supply  abundant  opportunity  for  the  rapid 
multiplication  of  the  weevils.  Severe  drought  checks  together  the 
growth  of  the  plant  and  the  development  of  the  weevils.  It  has  not 
yet  been  determined  whether  the  death  of  larvae  in  fallen  squares 
exposed  directly  to  the  rays  of  the  sun  is  due  principally  to  the  heat 
produced  or  to  the  complete  drying  of  the  food  supply.  It  is  certain, 
however,  that  one  or  both  of  these  factors  produce  a  large  mortality 
among  the  larva*  and  pupae  so  exposed  during  long-continued  hot  and 
dry  weather  occurring  before  the  plants  have  become  large  enough 
to  shade  most  of  the  ground.  After  that  the  shade  produced  pre- 
vents most  of  the  good  work  of  the  sun  in  destroying  weevils. 

It  is  often  said  by  cotton  growers  that  "rain  brings  the  weevils." 
The  principal  reasons  for  this  idea  are  that  rains,  in  squaring  time 
especially,  produce  conditions  greatly  favoring  the  immediate  devel- 
opment and  subsequent  injury  of  weevils,  while  at  the  same  time 
they  make  more  apparent  the  amount  of  injury  already  done.  An 
abundance  of  rain  following  a  long  dry  period  naturally  causes  greal 
numbers  of  squares  to  fall  from  purely  physiological  causes,  while  at 
the  same  time  it  knocks  to  the  ground  such  previously  infested 
squares  as  have  become  weakened  in  their  connection  with  the  plant 
and  which  would  fall  naturally  within  a  tew  days.  The  Large  number 
of  squares  to  be  found  on  the  ground  immediately  after  a  storm  would 
seem  to  account  for  the  prevalence  of  the  opinion  mentioned.  A 
large  degree  of  moisture  in  fallen  squares  seems  to  favor  directly  the 
2 1 7:59— No.  45—04 7 


98 

growth  of  larvae  within,  thus  producing  quickly  a  large  number  of 
weevils  ready  to  do  further  injury. 

It  is  still  an  open  question  as  to  how  low  winter  temperatures  the 
weevil  can  withstand.  It  is  certain  that  in  southern  Texas  many 
Larvae  and  pupae  slowly  continue  their  development  during  the  winter 
season.  Mr.  S.  G.  Borden,  of  Sharpsburg,  Tex.,  in  a  letter  written 
January  27,  1896,  says:  "Hands  clearing  up  cotton  stalks  report 
plenty  of  the  larvae  in  dry  bolls."  Mr.  Schwarz  found  weevils  hiber- 
nating in  ail  stages,  except  the  egg,  at  Victoria,  Tex.,  during  Febru- 
ary, 1902.  At  the  same  locality  in  January  and  February  of  1904,  the 
weevils  in  larval,  pupal,  and  adult  stages  were  taken  alive  from  dry 
bolls  by  Mr.  J.  D.  Mitchell,  a  resident  and  cotton  planter  of  that  place. 

After  the  weevils  first  made  their  appearance  at  San  Antonio  in  the 
fall  of  1895  they  were  supposed  to  have  been  entirely  destroyed  by 
frosts  during  the  following  winter.  The  lowest  temperature  recorded 
at  San  Antonio  for  that  winter  was  26°  F.  on  December  30,  1895. 
On  January  2,  1896,  Professor  Townsend  made  an  examination  of  the 
condition  of  the  weevil,  and,  so  far  as  he  found,  all  larvae  in  bolls  were 
then  dead,  while  pupae  and  adults  were  all  alive.  In  spite  of  the  mild- 
ness of  the  remainder  of  the  winter  the  weevils  did  no  damage  to  the 
crop  of  1896,  and  were  not  found  in  fields  in  which  they  were  present 
the  year  before.  In  writing  of  this  unexpected  condition,  on  October 
19,  1896,  Professor  Townsend  says,  "The  timely  drought  of  last  of 
May  and  first  of  June  is  what  killed  the  weevils  this  year."  There  is 
therefore  some  doubt  as  to  whether  frosts  or  drought  were  responsible 
for  the  destruction  of  the  weevils  at  San  Antonio  in  1896. 

At  Victoria,  on  February  17,  1903,  the  lowest  temperature  recorded 
by  the  Weather  Bureau  report  was  20°  F.,  but  many  weevils  hiber- 
nated successfull\\  Doubtless  much  lower  temperatures  than  this 
were  experienced  in  more  northern  localities  in  the  weevil  belt,  but 
in  no  place  have  the  weevils  been  exterminated  thereby. 

EFFECT   OF   RAINS   UPON   DEVELOPMENT   OF   WEEVILS. 

AVliile  it  is  a  mistaken  idea  that  rains  first  bring  the  weevils,  it  is 
true  that  they  favor  weevil  increase  in  several  ways.  Frequent  rains 
increase  the  growth  of  the  plant  and  lead  to  the  production  of  a  larger 
number  of  squares  which  may  become  infested.  Driving  rains  knock 
off  infested  squares,  and  by  softening  and  moistening  the  food  hasten 
the  development  of  the  larvae  within.  Squares  which  are  already 
upon  the  ground  are  protected  during  rainy  weather  from  sunshine 
and  drying.  Rain  hinders  the  enemies  of  the  weevil  far  more  than  it 
does  the  development  of  the  weevils  themselves.  In  several  such 
ways  rains  contribute  directly  or  indirectly  to  the  more  rapid  multi- 
plication of  weevils  and  cause  the  common  impression  among  cotton 
planters  alluded  to  above. 


99 

inn   i    OF   w  EST   WTNTKB    w  i:\tii  1,1;   ON    n  l  BERN  \  ti  \<  I    wi.i\m 

Owing  bo  the  writers'  absence  from  Victoria  during  the  winter 
months,  observations  could  not  be  made  directly  or  immediately  upon 

this  point.  It  was  found,  however,  that  all  weevils  iii  hibernation 
tests  which  passed  the  winter  successfully  had  been  kept  dry.  The 
winter  of  1902-  3  was  unusually  wet  at,  Victoria,  and  the  number  of 
hibernated  weevils  which  were  to  be  found  on  early  cotton  plants  was 
noticeably  less  than  during  previous  seasons  which  had  been  dry.  It 
semis  probable,  therefore,  that  as  many  weevils  perish  from  frequent 
wetting  as  from  exposure  to  the  cold. 

EFFECTS   OF   OVERFLOWS    IN    FIELDS. 
I '  nusuallv  favorable  conditions  for  these  observations  were  obtained 

at  Victoria  in  the  season  of  L903.  During  the  latter  part  of  February 
an  overflow  of  the  Guadalupe  River  covered  many  of  the  cotton  fields 
along  its  course.     The  fields  in  which  especial  study  was  made  were 

wholly  submerged  from  one  to  several  days.  Cotton  was  planted  in 
some  of  these  fields  between  March  15  and  17.  Owing  to  cold 
weather  the  growth  of  the  plants  was  delayed  and  squaring  did  not 
begin  until  between  May  10  and  17.  Immediately  after  this  date  it 
was  found  that  weevils  were  present  and  at  work,  and  fallen  squares 
were  first  found  about  May  23.  From  a  study  of  this  field  it  became 
apparent  that  the  overflow  had  caused  a  considerably  less  decrease 
than  had  been  anticipated  in  the  number  of  hibernating  weevils. 
Possibly  the  fact  that  the  winter  of  1002-3  had  been  exceptionally 
rainy  may  account  for  the  lack  of  contrast  in  weevil  abundance  in 
overflowed  fields  and  those  which  did  not  suffer  in  this  way  since,  as 
has  already  been  noted,  hibernated  weevils  were  unusually  scarce, 
even  on  uplands. 

Another  period  of  high  water  occurred  during  the  last  of  .June  and 
the  first  of  July  and  gave  a  convenient  opportunity  to  note  its  effect 
ui^on  active  weevils.  Many  fields  were  partially  and  some  wholly 
submerged.  This  condition  lasted  for  several  days.  Examination 
made  after  the  recession  of  the  water  showed  that  many  fallen 
squares  which  had  certainly  been  in  the  water  for  some  time  con- 
tained uninjured  larva'  and  pupae.  Naturally  eggs  and  larva' 
found  in  squares  upon  the  plants,  even  though  under  water  for  some 
time,  escaped  unharmed.  Weevils  were  working  normally  upon  the 
plants.  No  diminution  in  their  numbers  could  be  seen  and  it  was 
apparent  that  the  overflow  caused  no  check  either  to  the  develop- 
ment of  the  immature  stages  or  to  the  activity  of  the  adults.  These 
observations  emphasize  the  fact  that  the  weevil  can  not  be  drowned 
out. 


100 


LAI, ORATORY    OBSERVATIONS    UPON    TIME    WEEVILS   WILL    FLOAT    OR 
ENDURE    SUBMERGENCE. 

These  tests  were  divided  into  two  parts,  each  of  which  includes 
botli  the  immature  and  mature  stages.  In  each  part  floating  and 
submergence  were  tested. 

Sixty  squares,  believed  from  external  examination  to  be  infested, 
were  floated  in  a  driving  rain  for  six  hours.  They  were  then  removed 
and  left  for  several  days,  during  which  time  75  per  cent  of  them  pro- 
duced normal  adults.  Ten  squares  which  were  floated  in  driving  rain 
for  six  hours  were  opened  at  once,  and  in  every  case  found  to  be  but 
slightly  wet  upon  the  inside.  These  contained  6  larvae  and  4  pupae, 
and  all  were  in  perfect  condition. 

As  squares  float  normally,  submergence  tests  were  considered 
extreme.  Five  squares  were  submerged  for  six  hours,  and  after  that 
produced  3  normal  adults;  1  pupa  died,  and  1  square  was  found  to 
have  been  uninfested.  Five  more  squares  were  submerged  for  thirty- 
one  hours.  These  produced  2  normal  adults,  and  1  pupa  died  in  the 
process  of  molting  after  removal  from  the  square.  Death  was  prob- 
ably caused  in  the  last  case  by  drying;  1  square  was  found  to  contain 
a  dead  pupa,  and  1  was  not  infested.  To  test  the  possibility  of  its 
living,  should  the  square  be  penetrated  by  water,  a  naked  pupa  was 
submerged  for  six  hours,  but  in  spite  of  this  unusual  treatment  it 
produced  a  normal  adult. 

In  the  tests  made  upon  the  floating  power  of  adults,  weevils  were 
isolated  and  placed  in  water  in  tumblers.  They  were  dropped  from  a 
considerable  distance  above  the  surface,  so  that  they  became  entirely 
submerged,  and  then  floated  to  the  surface  naturally.  The  surface 
tension  of  the  water  was  found  to  be  sufficient  to  float  weevils  which 
were  placed  upon  it  carefully.  The  generally  hairy  condition  of  the 
surface  of  the  weevil's  body  prevents  its  being  readily  wetted,  so  that 
it  may  struggle  for  some  time  in  the  water  without  becoming  really 
wet.  When  dropped  in  this  way  weevils  float  head  downward,  with 
the  tip  of  the  abdomen  above  the  surface.  In  the  submergence  tests 
weevils  were  held  down  by  a  wire  screen,  and  all  bubbles  were 
removed  from  their  bodies  by  a  pipette,  thus  making  the  tests  as 
severe  as  possible. 


10 


T  \i'i  i    X  X  \  I     /.'//'  ctn  of  floating  <ni<i  aubnu  r</>  nee  on  all  .-/«»./. 


ConditloiiH  ..[  tenl 


Sim  \    squares    floated    In 

ram 

Ton  squares  floated  In  rain 


Five  squares  submerged 

1)..  

(  hoe  naked  pupa  submerged 
Ten  adults  floated 
Do.. 


Pive  adults  submerged 

Do  


I),-,, I       Tmi" 
Tims    ,V':    ,    before 

"'  ,,M   nation 


Nor 

mill 

adults 
best. 


Ten  adults  submerged 

Fourteen  adults  submerged 


Hours. 

i; 

i  to  - 

t; 

Nona 

None 

SI 

1  pupa 

5  to  8 
None 

e 

86 
112 

II 
ll 

1 

16 

0 

86 
48 

9 

u 

KouutrkH. 


."•  squares  contained  dead  larva*: 
:{  pupsa  destroyed  by  ants,  and  '. 
uninfested 

Squares  bnl  slightly  w.-t    Inside    B 

larva-    and    .">    pupSB    all    alive    and 

QormaL 
I  pupa  dead:  l  square  uninfested 

I   pupa  and  :.'  larva-  alive  aft 

squares  not  we\  much  inside. 


■"  feed,  but  i  died 
in  from  :'.  to  7  days;  l  lived  86  days 

and  laid  58  ■ 

:i  males  died  soon;  females  laid  48 

eggs  in  ir>  weevil-days. 
1  lived  through  test,  but  never  fed. 


Iii  the  case  of  squares  floating  normally  it  is  evident  that  they 
might  remain  in  water  for  several  days  without  injury  to  the  weevil 
within.  Very  slight  wetting  of  the  cell  takes  place  even  under  the 
ext  i-enie  conditions  of  submergence.  The  effect  of  a  brief  flood  would 
in ii,  therefore,  be  at  all  injurious.  As  adults  float  as  readily  as  do 
squares,  they  may  also  be  carried  long  distances,  and,  furthermore,  they 
arc  able  to  crawl  out  of  the  water  onto  any  bushes,  weeds,  or  rubbish 
which  they  may  touch.  Even  when  floating  for  several  days  continu- 
ously they  are  able  to  live  and  may  be  carried  directly  to  new  fields. 
The  floating  of  adults  and  infested  squares  explains  the  appearance 
of  weevils  in  great  numbers  along  high-water  line  immediately  after 
a  flood,  and  indicates  that  probably  the  most  rapid  advance  the  pest 
will  make  in  the  United  States  will  be  into  the  fertile  cotton  lands  of 
the  Red  River  Vallej'  in  Louisiana. 


PROBABILITIES   AS    TO    THE   INFLUENCE    OF    CLIMATE    OX    THE  WEEVIL 
IX   COTTON   REGIONS   XOT   NOW   IXFESTED. 

The  influence  which  the  lower  temperature  prevailing  over  the 
northern  edge  of  the  cotton  belt  may  have  upon  the  development, 
desl  iin-tiveness,  and  spread  of  the  weevil  is  as  yet  largely  problemat- 
ical. No  considerable  amount  of  accurate  data  upon  the  development 
of  the  weevil  being  at  present  available  except  that  collected  al  Vic- 
toria, Tex.,  during  the  seasons  of  1902  and  1903,  it  is  impossible  to 
predict  with  certainty  how  far  or  how  rapidly  the  weevil  may  spread 
or  the  rapidity  of  development  which  may  take  place  under  the  differ- 
ent climatic  conditions  prevailing  in  regions  not  at  present  infested, 
or  whether  it  may  be  expected  that  its  destructiveness  to  cotton  will 
be  materially  reduced  in  other  sections.  These  questions  are,  how- 
ever,  of  considerable  interesl   because  of  the  probability  that  the 


102 

weevil  will  ultimately  spread  over  the  entire  cotton  belt  in  spite  of 
any  measures  which  may  be  adopted  to  retard  its  progress. 

During  the  past  centuiy  the  attention  of  many  botanists  and  zool- 
ogists has  been  drawn  to  the  relations  existing  between  geographic 
areas  and  the  distribution  of  plants  and  animals.  In  this  country 
the  limits  of  the  well-defined  zones  and  the  laws  governing  the  distrib- 
ution of  plant  and  animal  life  through  those  zones  have  been  most 
carefully  determined  by  Dr.  C.  Hart  Merriam,  Chief  of  the  Division  of 
Biological  Survey  of  the  United  States  Department  of  Agriculture.0 
A  few  years  before  the  publication  of  Doctor  Merriam's  completed 
results  Dr.  L.  O.  Howard,  Chief  of  the  Division  of  Entomolog}^  first 
applied  the  principles  underlying  geographic  distribution  to  a  study 
of  the  probable  spread  of  a  number  of  species  of  very  injurious 
insects,  most  of  which  had  been  imported  into  this  country,6  and 
recently  he  has  made  a  more  extensive  study  of  a  very  practical 
nature  concerning  the  geographic  distribution  of  the  yellow  fever 
mosquito/  Many  observations  have  shown  that  in  general  the  limits 
of  the  spread  of  an  imported  insect  pest  may  thus  be  approximately 
determined.  It  is,  therefore,  not  out  of  place  to  consider  at  this  time 
some  points  in  regard  to  the  probable  status  of  the  boll  weevil  in  the 
cotton  belt  outside  of  Texas. 

According  to  the  map  published  by  Doctor  Merriam,  the  entire 
cotton-growing  area  of  the  United  States  lies  within  the  Lower  Austral 
Zone,  the  northern  limit  of  which  is  marked  by  the  isothermal  line 
showing  a  sum  of  normal  positive  temperatures  (above  32°  F.)  amount- 
ing to  18,000°  F.  The  weevil  has  alread}7  become  established  near  Sher- 
man, Tex.  As  nearly  as  can  be  told  from  data  at  present  available,  the 
isothermal  line  passing  through  Sherman,  if  extended  eastward,  would 
pass  along  the  Red  River  Valley,  through  the  extreme  southern  part 
of  Arkansas,  across  central  Mississippi  and  Alabama,  a  little  south  of 
Atlanta,  Ga.,  and  thence  curve  northeastward  through  South  and 
North  Carolina.  It  therefore  becomes  evident  that  "temperature" 
will  not  prevent  the  spread  of  the  weevil  eastward.  Even  if  it  should 
not  go  beyond  the  isothermal  line  within  which  it  now  thrives,  its 
territory  would  still  include  most  of  the  great  cotton  belt  of  the  United 
States.  Furthermore,  there  is  no  evidence  to  show  that  the  weevil  has 
yet  reached  its  most  northern  limit,  and  the  probabilty  remains  that  it 
may  yet  show  itself  capable  of  existing  anywhere  within  the  Lower 
Austral  Zone  where  cotton  can  be  grown. 

A  comparison  of  the  positive  temperatures  of  various  localities  in  the 

« Bulletin  10,  U.  S.  Dept.  Agr.,  Division  of  Biological  Survey,  Life  Zones  and 
Crop  Zones  of  the  United  States. 

&Proc.  Entorn.  Soc.  Washington,  Vol.  Ill,  No.  4,  pp.  219-226.  "Notes  on  the 
Geographic  Distribution  in  the  United  States  of  Certain  Insects  Injurious  to  Cul- 
tivated Crops."' 

c  Treasury  Department— Public  Health  Reports,  Vol.  XVIII,  No.  46.  'Con- 
cerning the  Geographic-  Distribution  of  the  Yellow  Fever  Mosquito." 


in:; 

northeastern  pari  of  iii«'  cotton  belt  with  thai  of  Victoria,  Tex.,  dur 
tag  the  si\  months  from  June  I  i<>  November  30,  L902,  naturally 
reveals  a  considerable  range  of  difference,  as  does  also  r  comparison 
of  lie  average  temperatures  prevailing  in  those  localities  during  the 
same  period  for  tin*  preceding  eleven  years.  Wherever  ii  Is  con 
Bidered  In  its  effect  upon  the  development  of  the  weevil  the  tempera- 
ture given  is  expressed  in  degrees  of  effective  temperature — that  is, 
the  actual  temperature  above  43  F.  The  mean  average  effective 
temperature  for  any  month  multiplied  by  the  number  of  days  included 
has  been  considered  as  giving  the  total  effect  ive  temperature  for  that 
month.  While  this  method  docs  not  give  exactly  the  correct  figures, 
ii  will  furnish  data  for  a  comparison  of  the  various  Localil Les,  and  this 
study  of  temperatures  will  undoubtedly  reveal  facts  which  will  exert 
considerable  influence  upon  the  status  of  the  weevil  in  other  loealii  ies 
into  which  it  is  liable  to  spread. 

The  total  effective  temperature  for  Victoria,  Tex.,  from  June  1  to 
November  30, 1902,  was  6,607°  F.  For  the  same  period  at  Dallas  Tex., 
it  was  5,626    F.,  and  at  Atlanta,  Ga.,  it  was  5,052°  F. 

The  average  mean  total  effective  temperatures  for  the  sections  of 
Texas,  Louisiana,  and  Georgia,  as  given  by  the  Weather  Bureau  for  a 
seriesof  eleven  years,  are  as  follows:  Texas,  5,710°;  Louisiana,  5,578  ; 
Georgia,  5,234°  F. 

The  effect  of  this  decrease  in  temperature  will  doubtless  be  in  some 
measure  counteracted  by  a  certain  degree  of  adaptation  thereto  on 
Hie  part  of  the  weevil,  but  it  still  seems  probable  that  in  the  tempera- 
ture of  Georgia  a  considerable  reduction  in  the  number  of  generations 
will  be  found.  The  emergence  from  winter  quarters  will  probable  be 
considerably  later  than  the  middle  of  April.  The  development  of 
progeny  will  not  be  as  rapid  as  has  been  described  for  Victoria,  Tex., 
in  preceding  pages.  Furthermore,  it  seems  likely  that  during  the 
warmest  periods  the  life  cycle  will  require  from  22  to  28  days.  The 
consequent  limited  number  of  generations  in  a  season  will  be  still 
further  curtailed  by  the  earlier  period  of  hibernation,  which  it  seems 
will  begin  as  early  as  the  latter  part  of  October  or  the  first  of  Novem- 
ber, instead  of  during  December,  as  was  the  case  during  the  past  t  wo 
years  at  Victoria.  The  date  of  the  killing  frosts  will,  in  a  general 
way,  fix  the  end  of  the  active  season  for  the  weevil,  and  this  will 
therefore  vary  considerably  from  year  to  year. 


104 


T  \i:i.k  XXVII. — Temperature  comparisons  of  various  cotton  sections. 


Month. 


Monthly  average  normal  mean  for  11  years,  1892-1902. 


Victoria, 
Tex.,av- 

erage 
(1902  and 

1903 
only). 


o  pi 

Jane T.").n 

July BO  - 

August 80.2 

September I  77.6 

October I  71.6 

November 63. 7 

Average  f < >r  6  months. .  74. 8 


Dallas, 
Tex. 


Shreve- 
port,  La. 


F. 

80.5 
83.3 
82.8 
77.4 
68.1 
56.7 


F. 

79. 9 
32  l 

::  - 

67.1 
56. 8 


r4.4 


Atlanta. 
Ga. 


F. 
78.0 
80.3 
79. 2 

70.2 
62. 6 

57. : S 


71.2 


Texas 
section. 


F. 

80.6 

88.9 

82.8 
77.3 
67.9 
57.3 


Louisi- 
ana sec- 
tion. 


80.1 
83. 5 
81.6 
77.1 
67.  7 
58.9 


r4.6 


UA 


Georgia 
section. 


78. 2 
80. 1 
79.0 

74.7 
64.5 
58.9 


12. 2 


From  these  considerations  of  temperature  difference  and  judging 
the  varying  influence  as  ascertained  at  Victoria,  it  seems  that  the 
weevil  may  prove  less  and  less  destructive  as  it  spreads  to  the  cooler 
portions  of  the  cotton  belt,  though  this  supposition  is  likely  to  be 
nullified  by  an  ability  to  adapt  itself  to  new  conditions. 

While  it  must  be  admitted  that  nothing,  so  far  as  now  known,  seems 
certain  to  prevent  the  spread  of  the  weevil  to  any  latitude  where  cotton 
is  now  grown,  it  does  seem  probable  that  its  control  ma}'  be  more  easily 
accomplished  in  the  more  northern  portions  of  the  cotton  belt  than  in 
the  Texas  area  now  infested,  and  since  it  has  been  most  positively 
demonstrated  that  better  than  the  average  crop  may  here  be  grown 
in  spite  of  the  depredations  of  the  weevil,  there  would  seem  to  be  no 
special  reason  for  a  panic  over  the  future  of  the  cotton  crop.  Cotton 
has  been  and  still  will  be  grown  in  spite  of  the  weevil.  The  present 
promise  is  that  those  planters  who  enter  the  struggle  with  determina- 
tion, and  who  adopt  the  advanced  methods  which  have  proven  suc- 
cessful wherever  tried,  will  realize  practically  as  large  a  profit  from 
cotton  raising  in  the  future  as  it  has  been  possible  to  obtain  in  the 
past. 

DISEASES. 

Especially  in  moist  breeding  jars,  weevils  often  die  from  what 
appears  to  be  a  bacterial  disease.  The  body  contents  liquefy,  turning 
to  a  dark  brown  in  color,  and  have  a  putrid  odor.  Death  follows 
quickly,  though  not  until  after  putrefaction  has  begun.  The  fre- 
quency with  which  several  weevils  died  in  the  same  jar  at  about  the 
same  time  indicates  that  this  disease  may  be  contagious.  It  has  not 
been  found  in  the  fields,  however,  and  may  have  been  due  entirely  to 
abnormal  laboratory  conditions. 

It  is  doubtful  whether  the  following  observations  upon  fungus 
attacks  upon  weevils  should  properly  be  classed  with  diseases,  but  as 
there  is  a  possibility  that  the  attack  may  have  been  of  this  nature,  the 
observations  may  be  given  here. 

In  July,  19<>2,  a  lot  of  squares  sent  by  mail  from  Calvert,  Tex.,  to 
Victoria,  was  so  long  delayed  upon  the  road  that  they  were  very 


105 

mold}  when  received.  Thirteen  apparently  healthy  pupae  were 
removed  from  these  moldy  squares  with  the  intention  of  rearing  1 1 m * 
adults.  The  pupae  were  kepi  moist,  and  in  a  shorl  time  5  died, 
apparently  from  the  attacks  of  an  unknown  species  of  fungus.  The 
remainder  were  then  kept  dry,  i>ui  in  spit*'  of  this  precaution  6  more 
died,  only  2  becoming  adult.  In  another  Lot  of  27  pup®,  5  died, 
apparently  from  attacks  of  the  same  fungus. 

Specimens  of  the  dead  pupae  were  scut  to  the  pathologist  of  the 
Bureau  of  Plant  [ndustry  of  ili<'  Department  for  determination  of  the 
fungus,  h  was  pronounced  to  be  a  probably  new  species  of  Asper- 
gillus. As  no  species  of  this  genus  is  known  to  be  parasitic,  it  may 
be  thai  the  pupae  died  from  some  other  cause  and  thai  the  fungus  was 
entirely  saprophytic.  The  external  appearance  of  Hie  fungus  so  soon 
after  the  death  of  the  pupae,  the  large  mortality  prevailing,  and  the 
known  fact  thai  pupae  develop  uninjured  in  the  presence  of  many 
species  of  molds  leads  to  the  suspicion  that  it  may  have  had  some 
pari  in  causing  the  death  of  the  insects. 

In  L894  Prof.  ('.  II.  T.  Townsend,  while  engaged  in  the  study  of 
the  boll  weevil,  found  in  a  field  at  San  Juan  Allende,  Mexico,  a  speci- 
men of  a  dead  pupa  which  had  been  attacked  by  a  species  of  paiasit  ic 
fungus  (Cordyceps  sp.).  As  no  other  cases  of  attack  by  this  fungus 
have  been  reported,  its  occurrence  is  probably  very  rare. 

PARASITES. 

BREEDING    OF   PARASITES. 

Owing  to  the  importance  attached  to  parasites  in  the  control  of 
many  pests,  considerable  time  has  been  devoted  to  the  rearing  of  para- 
sitic enemies  of  the  boll  weevil.  From  the  very  nature  of  the  habits 
of  the  weevil,  no  perfectly  satisfactory  method  of  breeding  these  para- 
sites could  be  devised.  The  apparatus  used  was  exceedingly  simple. 
Squares  which  were  thought  to  be  infested  were  picked  or  gathered 
in  the  field,  and  cleared,  so  far  as  was  possible,  of  all  that  might  pro- 
duce parasites  not  developed  from  the  weevils.  Small  lots  of  these 
squares  were  placed  in  paper  bags,  each  fitting  tightly  over  the  open 
mouth  of  a  glass  jar.  As  both  parasites  and  weevils  upon  emergence 
naturally  make  their  way  to  the  light,  they  could  easily  be  seen  in  the 
glass  jars  and  at  once  removed.  Even  when  thus  bred  something 
must  be  known  of  the  habits  of  each  species  of  insect  produced  or  of 
its  close  allies  to  determine  whether  it  is  really  a  parasite  upon  a 
w^eevil  larva,  a  hyperparasite,  or  merely  a  vegetable  feeder  devel- 
oped in  the  decaying  square.  Many  small  flies  breed  in  such  decaying 
matter  and  were  caught  in  the  jars,  but  these  must  all  be  acquitted  of 
being  parasites  upon  the  weevil.  The  results  are  therefore  made 
somewhat  uncertain  because  of  the  impossibility  of  isolating  the 
weevil  larvae.  A  condensed  summary  of  the  results  in  breeding 
parasites  through  two  seasons'  work  is  presented  in  Table  XXVIII. 


106 


TABL  EC  XX  VIII . — B reeding  of  parasites. 


Collector. 

Weevils 
bred. 

Parasites. 

Locality. 

Date. 

Squares. 

Bracon 
mellitor. 

Other 

spe- 
cies. 

Sguarespickedfrom  plants 

mill  from  ground. 

Calvert,  Tex 

G.H.Harris 

W.E.Hinds. 

1902. 
July,  August 
do 

2,566 
645 

387 

881 
4(13 

342 

277 

210 

108 

278 
111 
251 

120 

3 
1 

1 

10 
3 
0 

45 

1 
1 

fW.D.  Hunter.... 
JW-E.  Hinds 

W.E.Hinds 

do 

J-  August 

1903. 
June 

0 

0 

Do 

July 

1 

Do 

...do 

August 

July,  August 

0 

Infested  squares  dried  on 
the  plants. 

W.E.Hinds 

Total 

5,548 

1,355 

63 

8 

From  these  observations  it  appears  that  24.4  per  cent  of  the  5,548 
squares  used  produced  adult  weevils,  while  only  1.3  per  cent  of  the 

total  squares  contained 
parasites.  Among  the 
parasites  obtained,  90  per 
cent  were  of  the  single 
species  Bracon  mellitor 
Say  (fig.  4).  A  single 
specimen  of  another  un- 
doubtedly primary  para- 
site ,  Sigalp  li  us  c  1 1  rcul  io  / 1  is 
Fitch,  was  reared.  A  few 
specimens  of  Catolaccus 
incertus  Ashm.  may  pos- 
sibly have  come  from  the 
weevil  larva?,  but  were 
more  likely  hyperpara- 
sites.  According  to  the 
authority  of  Dr.  William 
II.  Ashmead,  of  the 
United  States  National 
Museum,  to  whom  the  writer  is  indebted  for  the  specific  determina- 
tions and  also  for  information  about  the  usual  habits  of  these  para- 
sitic insects,  the  following  species,  which  were  bred  from  squares, 
must  probably  be  credited  to  some  other  host  than  the  boll  weevil: 
Chalcis  coloradensis  Cress,  and  Goniozus  platynotce  Ashm.  were  prob- 
ably upon  lepidopterous  larva?;  Eurytoma  sp.  and  Eupelmus,  two 
spp.,  usually  attack  dipterous  larva?  in  galls  and  a  number  of  speci- 
mens of  a  species  of  Ooencyrtus  may  have  been  parasitic  upon  the 
eggs  of  some  lepidopteron  or  hemipteron,  but  certainly  could  not 
have  reached  the  eggs  of  the  weevil. 


Fig.  4. 


-Bracon  mellitor,  parasite  of  boll  weevil— much 
enlarged  (original). 


1<)7 


H  la  \,-i\  noticeable  that  the  dried  squares  which  were  picked  from 
the  plants  produced  by  far  the  largesl  part  of  all  the  parasites  obtained, 
.'ill'  Bquares  giving  •">(|  parasites.  In  this  lot,  therefore,  I  I  per  •••■m  <>f 
the  total  number  contained  parasites  of  some  kind  and  13  per  cent 
were  undoubtedly  developed  from  the  weevil  Larv».  Taking  all  other 
squares  together,  5,286  yielded  only  L8  primary  parasites,  or  onlj  0.3 
per  cent. 

Previous  efforts  to  breed  parasites  of  the  weevil  yielded  a^  meager 
results  as  those  which  have  just  been  recorded,  though  they  add  to 
the  number  of  species.  Iu  L894  Prof.  C.  II.  T.  Townsend  bred,  ai 
Corpus  Christ i,  Tex.,  a  single  specimen  of  Urosigalphus  robustus 
Ashm.,  which  was  in  all  probability  a  primary  parasite,  as  was  also 
Bracon  dorsata  Say,  of  which 
Mr.  Scli war/  obtained  two 
specimens  at  Goliad,  Tex.,  in 
the  fall  of  L895.  A  specimen 
of  Ewrytoma  tylodt  rmatis 
Ashm.,  also  reared  by  Mr. 
Townsend,  may  possibly  have 
had  some  other  host. 

Pedieuloides  Vi  rvtricosus 
Newp. — This  small  mite  has 
been  thought  by  some  scien- 
tists to  be  the  most  promising- 
parasite  yet  found  attacking 
the  weevil.  It  has  been  ex- 
perimented with  quite  exten- 
sively by  Prof.  A.  L.  Herrera 
and  his  assistants  of  the  Mexi- 
can Commission  of  Parasi- 
tology. The  mites  breed  with 
extreme  rapidity,  the  larvseof 
wasps  being  their  usual  hosts. 
Both  sexes  attain  full  physical 

and  sexual  maturity  while  yet  within  the  body  of  the  mother.  The 
males  are  exceedingly  tiny,  as  are  also  the  females,  when  they  first 
leave  the  mother  mite.  As  the  females  become  gravid,  however,  their 
abdomens  swell  to  an  astonishing  size  as  compared  with  the  rest  of 
the  body,  being  distended  by  the  rapid  growth  of  the  young  mites 
(fig.  5).  When  these  are  born  the  mother  dies,  while  the  offspring 
mate,  and  then  immediately  begin  the  search  for  food.  The  idea  of 
the  Mexican  investigators  was  that  these  tiny  parasites  would  be  able 
to  enter  the  square  through  microscopic  orifices  in  the  outer  layers, 
and  that  they  would  attack  and  destroy  the  weevil  larva3  and  pupae 
within.  Upon  his  return  from  a  trip  to  Mexico  in  the  fall  of  1902, 
the  senior  author  brought  with  him,  through  the  kindness  of  Pro- 


Fig.").— Enemy  of  cotton  boll  weevil,  Pedit  ruloidU  s  w  /<- 
tricosvs— much  enlarged  (adapted  from  Brucker). 


108 

fessor  Ilerrera,  a  supply  of   the  parasites,  from  which  others  were 
reared  for  experimental  work  in  Texas. 

In  the  course  of  these  experiments  the  possibility  of  the  mites 
attacking  larvae,  pupa3,  or  immature  adults  was  tested.  The  obser- 
vations made  failed  to  show  any  positive  ability  on  the  part  of  the 
IVdiculoides  to  penetrate  the  squares,  as  in  only  two  cases  were  mites 
found  in  them  and  attacking  the  larva?.  In  these  two  cases  it  seems 
entirely  possible  that  the  mites  may  have  entered  through  feeding 
punctures  or  some  other  rupture  in  the  floral  envelopes. 

Upon  several  occasions  during  the  season  of  1903  mites  were  dis- 
tributed in  badly  infested  cotton  fields.  Later  examinations  were 
carefully  made,  but  they  failed  to  show  that  the  parasites  had  gained 
a  hold  or  even  that  they  had  attacked  the  weevils  in  any  stage. 

These  mites,  if,  indeed,  they  are  of  the  same  species  as  those  de- 
scribed by  Newport,  are  widely  distributed  and  attack,  to  some 
extent,  quite  a  large  number  of  insects.  If  they  really  possessed  the 
ability  to  get  at  the  weevil  larva?  and  the  predisposition  to  attack 
them  when  they  could  get  to  them  in  preference  to  other  hosts,  they 
should  certainly  have  shown  something  of  these  capabilities  some- 
where within  the  infested  area  in  Texas  during  the  ten  years  that  the 
weevil  has  been  found  there.  As  no  such  ability  has  yet  been  shown, 
we  doubt  that  the  Pediculoides  will  ever  prove  of  any  value  as  a  par- 
asite of  the  weevil  in  the  United  States,  though  it  may  be  more  effi- 
cient in  more  southern  countries.  Furthermore,  it  is  said  that  even 
where  the  mites  do  become  established  they  are  so  subject  to  the 
attacks  of  small  ants  that  their  efficiency  becomes  largely  destroyed. 

Several  attempts  have  been  made  by  agents  of  this  Division  to 
breed  parasites  of  the  weevil  in  localities  which  must  be  much  nearer 
its  original  home  than  is  Texas,  but  thus  far  these  attempts  have 
proven  as  fruitless  as  have  those  made  in  Texas.  It  seems  desirable 
that  this  work  should  be  continued  so  as  to  give  a  more  complete 
knowledge  of  all  the  parasites  of  the  weevil  in  its  native  home. 

These  results  show  how  insignificant  is  the  part  which  insect  para- 
sites play  in  the  problem  of  controlling  the  boll  weevil  in  Texas. 
The  thorough  protection  of  all  immature  stages  of  the  weevil  by 
several  layers  of  vegetable  matter  and  the  protection  of  the  adult  by 
its  hard,  closely  fitting,  chitinous,  external  plates  renders  very  small 
the  hope  that  any  parasite  will  ever  become  an  efficient  factor  in 
controlling  this  dangerous  pest. 

There  is  at  present,  therefore,  no  promise  of  any  considerable 
assistance  in  the  control  of  the  weevil  by  any  parasite  now  known. 
Because  of  its  peculiar  life  history  the  weevil  is  unusually  exempt 
from  the  attacks  of  parasites.  Even  should  one  be  found  which 
could  attack  the  weevil  in  some  stage,  it  would  probably  still  fail  to 
be  an  efficient  means  of  control,  because,  from  the  very  nature  of  its 
parasitic  habits,  it  is  bound  to  be  behind  the  weevil  both  in  the  point 


L09 

of  d umbers  and  in  the  time  of  its  activity.  While  such  parasites 
might  Berve  to  decrease  the  numbers  of  the  wreevil,  everj  larva  thai 
becomes  parasitized  has  already  done  its  damage  toa  square. 

In  spite  of  the  preseul  unpromising  outlook  for  the  discover}  of 
valuable  parasites  of  the  weevil,  every  effort  to  find  Buoh  should  i><- 
made.  WTiile  earnestly  hoping  that  effective  parasites  maj  yet  be 
discovered  or  developed,  it  is  folly  for  planters  to  neglect  <>r  delay 
the  adoption  of  those  methods  of  decreasing  wreevil  injury  which 
have  already  proven  to  be  both  practical  and  effective. 

PREDATORY    ENEMIES. 
INSECTS. 


Insects  which  prey  upon  the  boll  weevil  appeal-  to  be  even  fewer  in 
number  of  species  than  are  those  which  are  parasitic  upon  it.  The 
principal  enemies  of  this  class  are  ants, 
and  where  common  these  probably  destroy 
more  immature  weevils  than  do  the  para- 
sites. They  are  frequently  to  be  found 
in  squares  on  the  ground  in  the  act  of 
destroying  larva1  or  more  often  pupae. 
( Occasionally  they  have  been  found  enter- 
ing infested  bolls  which  are  yet  hanging 
upon  the  plants  and  destroying  the  pupa', 
which  had  become  exposed  by  the  prema- 
t  u  re  cracking  open  of  their  cells.  In  some 
eases  they  have  been  known  to  destroy 
young  adults  which  had  emerged  but  not 
become  fully  hardened.  Several  species 
of  ants  are  concerned  in  this  good  work. 
The  most  active  is  a  small  red  ant,  Sole- 
nopsis  debUis  var.  texana  Mayer?  (fig.  6). 
Another  species  belonging  to  the  genus  Myrmica  also  does  considerable 
good. 

Occasionally  there  may  be  seen  upon  cotton  plants  specimens  ol  a 
mantis,  or  "devil  horse,"  as  it  is  more  commonly  called.  One  species 
only,  Stagmomantis  limbata  Halm.,  has  been  carefully  tested  for  its 
ability  to  destroy  weevils.  A  male  of  this  species  was  confined  in  a 
breeding  cage  and  supplied  with  a  number  of  adult  weevils.  Sev- 
eral times  it  was  seen  to  seize  a  weevil  and  attempt  to  eat  it,  but 
being  unable  to  break  through  the  hard  chitinous  plates  which  ><» 
closely  cover  the  weevil's  body,  it  gave  up  the  attempt  and  let  the 
weevil  go  unharmed.  Although  kept  for  some  time  with  weevils  in 
its  cage,  it  never  fed  upon  them,  but  starved  to  death  in  their  pres- 
ence. With  the  female  of  this  species  the  case  is  quite  different. 
One  was  confined  in  a  cage  and  supplied  with  an  abundance  of  wee- 


Fig.  6.— Solenopais  debilis  var.  tex- 
anal  ant  enemy  of  l»oll  weevil — 
much  enlarged  (original). 


110 

vils.     It  seemed  to  be  more  powerful  than  the  male,  breaking  through 

the  weevil's  skeleton  with  apparent  ease.  On  several  occasions  it 
was  found  to  eat  8  or  10  weevils  a  day.  During  her  period  of  con- 
finement in  the  cage  she  deposited  a  large  batch  of  eggs,  and  in  the 
course  of  about  three  weeks  she  destroyed  altogether  a  total  of  80 
weevils. 

Some  species  of  Mantispa  also  probably  devour  a  few  weevils  in  the 
field,  but  the  writer  has  never  seen  one  in  the  act. 

BIRDS. 

There  can  be  no  doubt  that  birds  are  exceedingly  valuable  assist- 
ants to  man  in  reducing  the  numbers  of  many  insect  pests.  In  order 
to  determine  to  what  extent  they  feed  upon  the  boll  weevils,  it  is  nec- 
essary that  an  extensive  study  be  made  of  the  stomach  contents  of  all 
birds  that  may  be  found  in  cotton  fields.  To  be  at  all  conclusive 
such  studies  must  be  made  in  numerous  localities  and  during  more 
than  one  season.  To  accomplish  this  it  is  deemed  advisable  to  reserve 
for  the  present  the  results  of  the  studjr  of  the  relation  of  birds  to  the 
weevil  problem,  that  a  more  complete  treatment  of  the  question  may 
be  made  in  some  future  publication. 

METHODS  OF  COMBATING  THE  WEEVIL. 

The  difficulties  in  the  way  of  controlling  the  boll  weevil  lie  as  much 
in  its  habits  and  manner  of  work  as  in  the  peculiar  industrial  condi- 
tions involved  in  the  production  of  the  staple  in  the  Southern  States. 
The  facts  that  the  weevil  lives  in  all  stages  except  the  imago  within 
the  fruit  of  the  plant,  well  protected  from  any  poisons  that  might  be 
applied,  and  in  that  stage  takes  food  normally  only  by  inserting  its 
snout  within  the  substance  of  the  plant;  that  it  is  remarkably  free 
from  parasites  or  diseases;  that  it  frequently  occupies  but  14  days  for 
development  from  egg  to  adult,  and  the  progeny  of  a  single  pair  in  a 
season  may  reach  134,000,000  individuals;  that  it  adapts  itself  to 
climatic  conditions  to  the  extent  that  the  egg  stage  alone  in  Novem- 
ber may  occupy  as  much  time  as  all  the  immature  stages  together  in 
July  or  August,  are  factors  that  combine  to  make  it  one  of  the  most 
difficult  insects  to  control.  It  is  consequently  natural  that  all  the 
investigations  of  the  Division  of  Entomology  have  pointed  toward 
the  prime  importance  of  cultural  methods  of  controlling  the  pest. 
All  other  methods  must  involve  some  direct  financial  outlay  for 
material  or  machinery,  and  are  consequently  not  in  accord  with 
labor  conditions  involved  in  cotton  production  in  the  United  States. 
Moreover,  the  cultural  methods  are  in  keeping  with  the  general  tend- 
ency of  cotton  culture;  that  is,  to  procure  an  early  crop,  and  at  the 
same  time  have  the  great  advantage  of  avoiding  damage  by  a  large 
number  of  other  destructive  insects,  especially  the  bollworm.  Never- 
theless, it  must  not  be  understood  that  attention  has  not  been  paid 


1 1 1 

to  the  investigation  of  means  Looking  toward  the  extermination  of 
the  pest.  Asa  matter  of  fact,  everj  suggestion,  from  the  possibility 
o\'  breeding  resistant  varieties  to  the  use  of  electricity  in  destroying 
the  weevil,  has  been  fully  investigated.  The  results  have  all  been 
negal  ive. 

CULTURAL  METHODS. 

The  cultural  method  begins  with  reducing  the  numbers  <>f  the  pest 
in  the  fall  by  the  destruction  of  the  plants  as  soon  as  it  becomes  appar- 
ent that  no  more  cotton  is  to  be  produced.  The  enormous  importance 
of  this  procedure  is  shown  by  the  fact  already  stated  (p.  82)  that  the 
late  issuing  weevils  arc  the  ones  which  successfully  hibernate.  Fur- 
ther strong  reasons  are  given  on  pages  91  and  92j  under  the  sections 
"  Relations  of  weevils  to  top  crop"  and  "Some  reasons  for  the  early 
destruction  of  stalks."  Hosts  of  weevils  may  thus  be  killed,  a  very 
small  percentage  surviving  the  winter,  and  in  the  same  operation  the 
ground  is  better  prepared  for  planting  the  following  season.  A  large 
proportion  of  t  he  weevils  thus  destroyed  would  otherwise  pass  through 
the  winter  successfully  and  increase  the  damage  to  the  planted  cotton 
the  following  season.  Wherever  the  cotton  is  allowed  to  stand  in  the 
fields  in  the  hope  that  a  top  crop  may  be  produced  opportunities  are 
furnished  for  the  development  of  a  very  large  number  of  weevils.  As 
explained  before  in  this  bulletin,  the  possibility  of  a  top  crop  has 
always  been  exceedingly  remote.  Wherever  the  weevil  exists  it  is 
not  a  possibility  at  all.  The  method,  of  fall  destruction  onty  involves 
applying  labor  that  is  necessaiy  in  any  case  in  preparing  the  land  for 
planting  a  few  months  earlier  than  is  the  normal  practice  among 
cotton  planters.  It  has  been  the  custom  to  leave  the  land  uncleared 
until  shortly  before  planting  time  in  the  spring.  Now,  however,  this 
clearing  process  is  necessary  as  the  last  step  in  the  production  of  the 
preceding  crop.  This  method,  as  a  matter  of.  fact,  is  the  only  practi- 
cable strictly  remedial  method  that  has  been  devised. 

Simple  uprooting  of  the  plants  by  means  of  plows,  and  burning 
them  as  soon  as  sufficiently  dry,  is  very  effective;  but  undoubtedly 
the  most  effective  way  would  be  to  leave  a  row  out  of  20  after  the  gen- 
eral uprooting  has  taken  place,  to  serve  as  a  trap.  When  the  weevils 
have  assembled  upon  these  plants  they  might  be  killed  easily  with 
crude  petroleum,  as  the  destruction  of  the  plants  at  that  time  would 
be  immaterial.  Nevertheless  the  heaps  of  drying  stalks  also  act  as  a 
trap,  and  consequently,  especially  in  view  of  the  success  that  attends 
the  method,  the  average  planter  will  believe  the  destruction  of  all  the 
plants  in  the  field  a  better  plan  than  any  modification  of  it. 

The  remaining  portion  of  the  cultural  method  consists  in  furthering 
the  advantage  gained  by  fall  destruction  by  bending  every  effort 
toward  obtaining  a  crop  that  will  mature  before  the  weevils  have  had 
an  opportunity  to  do  considerable  damage.  The  most  important  fac- 
tors in  obtaining  an  early  crop  are  early  planting,  selection  of  a 


112     ' 

rapidly  growing  variety,  fertilization,  and  thorough  cultivation.  The 
success  of  the  planter  will  be  indirect  proportion  to  the  extent  to 
which  he  is  able  to  combine  these  essentials.  Early  planting  of  early 
varieties  will  be  found  to  be  of  comparatively  little  avail  unless  fol- 
lowed by  thorough  cultivation,  and  in  case  of  unavoidably  delayed 
planting  the  best  hope  of  the  planter  will  be  in  persistent  cultivation. 
As  the  details  of  the  cultural  method  have  been  dealt  with  fully  in 
the  Farmers'  Bulletins  of  this  Department,  and  as  the  basis  for  them 
in  the  habits  of  the  weevil  Avas  fully  explained  in  the  preceding  pages, 
it  is  unnecessary  in  this  connection  to  more  than  summarize  them : 

(1)  Fall  destruction. 

(2)  Early  planting  of  rapidly  maturing  varieties. 

(3)  Wide  spacing,  which,  besides  favoring  rapid  maturity  of  the 
plant,  also  acts  as  a  remedial  measure  by  allowing  the  sun  to  reach 
the  ground  and  causing  the  diying  up  of  the  squares  in  which  the 
larva1  occur. 

(4)  Thorough  cultivation. 

(5)  Fertilization  with  commercial  preparations  containing  high  per- 
centage of  phosphoric  acid. 

In  addition  to  this  general  system  that  is  applicable  to  all  cotton 
plantations,  favorable  labor  conditions  sometimes  make  it  feasible  to 
pick  the  infested  squares  by  hand.  Nothing  could  be  more  out  of 
place  than  to  suggest  hand  picking  upon  large  plantations.  Even  with 
convict  labor  it  has  been  found  entirely  impracticable.  But,  never- 
theless, where  a  planter  has  onty  a  few  acres  of  cotton  and  there  is 
an  abundance  of  cheap  labor,  such  as  that  of  children,  the  method 
has  been  found  very  effective. 

FUTILE  MEANS. 

The  very  serious  nature  of  the  boll  weevil  problem  is  constantly 
illustrated  by  the  manner  in  which  various  useless  devices  and  nos- 
trums are  brought  to  public  attention.  At  one  time  it  was  widely 
spread  about  that  mineral  paint  would  act  as  a  specific  against  the 
weevil.  An  equally  fallacious  theory  that  also  received  considerable 
popular  attention  was  to  the  effect  that  cotton-seed  meal  exerted  a 
powerful  attraction  for  the  pest. 

Probably  the  most  important  useless  recommendation  has  been  that 
of  spraying.  It  was  supposed  for  some  time  by  certain  parties  that  it 
might  be  possible  to  poison  weevils  economically  by  attracting  them 
to  some  sweetened  preparation.  The  experiments  detailed  on  i>ages  52 
to  56  of  this  bulletin  regarding  the  attraction  of  various  sweetened 
substances  demonstrate  the  fallacy  of  the  theory.  Even  if  these  sub- 
stances exerted  as  much  attraction  as  was  supposed,  there  would  be 
insurmountable  difficulties  in  the  application  of  the  method  in  the 
field.  Spraying  of  a  field  crop  has  never  been  a  success  and,  unless 
entirely  new  methods  are  eventually  perfected,  never  will  be  of  any 
practical  importance.     It  is  true  that  it  is  possible  to  destroy  a  cer- 


I  1:; 

lain  Qumber  of  weevils  in  regions  where  > » - j > i * -•  i  cotton  occurs  by 
ln'.-i\  il\  spraying  the  earliest  plants,  bul  this  method  is  of  immeasur- 
ably less  importance  than  the  simple  practice  of  cultural  methods. 

Many  attempts  have  been  made  to  perfect  a  machine  thai  will  ass  is  I 
in  the  warfare  againsl  the  weevil.  They  have  been  designed  to  poison 
the  insects,  to  jar  them  and  infested  squares  from  tin-  plain  and  to 
colled  them,  to  pick  the  fallen  squares  from  the  ground,  to  kill  by 
fumigation,  and  to  burn  all  infested  material  on  the  ground.  The 
Division  of  Entomology  has  carefully  investigated  the  merits  of  repre- 
sentatives of  all  of  these  classes,  beginning  in  L895  with  a  square- 
collecting  machine  thai  had  attracted  considerable  local  attention  in 
BeeCounty.  CTpto  the  present  time  none  of  these  devices  have  been 
round  to  be  practicable  or  to  offer  any  definite  hope  of  being  even- 
tually successful.  At  one  time  there  was  some  hope  thai  a  machine 
designed  to  pick  the  squares  from  the  ground  by  suction  mighl  be 
perfected.  The  experiments,  however,  have  indicated  probably  in- 
surmountable difficulties;  and  an  implement  concern,  after  having 
experimented  with  the  matter  fully  and  after  having  expended  over 
15,000,  lias  come  to  the  conclusion  that  mechanical  difficulties  will 
always  prevent  the  perfection  of  such  a  machine.  If  it  were  not  pos- 
sible to  raise  cotton  profitably  without  the  use  of  a  machine,  the  situ- 
ation would  be  changed  materially;  but  since  it  is  possible  to  produce 
the  staple  without  the  use  of  any  other  means  than  those  which  enter 
into  cotton  culture  everywhere,  there  seems  nohope  for  these  machines. 

BIBLIOGRAPHY. 

This  bibliography  includes  only  the  more  important  writings  which 
have  been  published  in  permanent  form.  It  does  not  include  the 
main'  hundreds  of  titles  of  articles  published  in  newspapers  and  in 
popular  magazines. 

1843.  Bokeman,  C.  II. — Genera  et  Species  Curculionidum  cum  Syn- 
onymia  hujus  Familiar  ed.  C.  J.  Shonherr  Vol.  V,  pt.  2,  pp. 
232-233. 

The  original  description  of  Anthonomus  grandis. 

1 87 1 .  Suffriax,  E. — Verzeichniss  der  von  I)v.  Gundlach  auf  der  Insel 
Cuba  gesammelten  Riisselkafer.  Archiv.  f.  Naturg.  XXXVII 

Jahrg.  13,  pt.  1,  pp.  130-1 31. 

Contains  the  record  of  a  specimen  from  Cardenas  and  one  from  San  Cris- 
tobal, in  Cuba. 

1885.  Riley,  C.  V. — Report  of  the  Commissioner  of  Agriculture,  f. 
1885,  p.  279. 

Contains  the  sentence  ''Another  very  large  species.  .1.  grandis  Boh.,  we 
have  reared  at  this  Department  from  dwarfed  cotton  bolls  sent  from  north- 
ern Mexico  by  Dr.  Edward  Palmer."     This  is  the  first  published  record  of 
the  food  plant  and  method  of  injury  of  the  species. 
21739— No.  45—04 8 


114 

1891.  Dietz,  W.  G. — Revision  of  the  Genera  and  Species  of  Antho- 
nomini  inhabiting  North  America.  Trans.  Am.  Ent.  Soc, 
Vol.  XVIII,  p.  205. 

The  species  is  here  reported  from  Texas.     It  has  been  shown,  however, 
that  this  was  an  error.     See  Insect  Life.  Vol.  VII,  p.  273. 

1894.  Howard,  L.  O. — A  new  Cotton  Insect  in  Texas.     Insect  Life, 

Vol.  VII,  p.  273. 

The  first  authentic  account  of  the  occurrence  of  the  species  in  the  United 
States,  and  some  statements  regarding  its  life  history. 

1895.  Howard,  L.  O.— The   New  Cotton-boll  Weevil.     Insect    Life, 

Vol.  VII,  p.  281. 

Regarding  the  importance  of  the  pest  and  the  investigation  started  by  the 
sending  of  Mr.  C.  H.  T.  Townsend  to  Texas  in  December.  1894. 

1805.  Towxsexd,  C.  H.  T. — Report  on  the  Mexican  Cotton-boll  Weevil 
in  Texas  (Anthonomus  grandis  Boh.).  Insect  Life,  Vol.  VII, 
Xo.  4,  pp.  295-309,  figs.  30,  31.     March. 

1S95.  Howard,  L.  O. — The  Mexican  Cotton-boll  Weevil.  Circular 
Dlv.  Ent.,  IT.  S.  Dept.  Agric,  Xo.  6  (second  series),  pp.  5, 
figs.  1-3,  April. 

1895.  Rios,  J.  R. — Aparicion  del,  "Picudo"  en  la  Laguna.     El  Pro- 

greso de  Mexico,  August  15,  1895. 

1896.  Howard,  L.  O. — The  Mexican  Cotton-boll  Weevil,  Circular  14, 

Div.  Ent.,  U.  S.  Dept.  Agric.  (second  series),  pp.  8,  figs.  1-5. 
A  revision  of  Circular  Xo.  6. 

1897.  Howard,  L.  O.— The  Mexican  Cotton-boll  Weevil,  Circular  18, 

Div.  Ent.,  U.  S.  Dept.  Agric.  (second  series),  pp.  8,  figs.  1-5. 
A  revision  of  Circular  Xo.  14.     It  was  issued  in  English.  Spanish,  and 
German  editions. 

1897.  Rios,  J.  R. — Aparicion  del  "Picudo"  en  la  Laguna.     El  Pro- 
greso  de  Mexico,  Vol.  IV,  pp.  811-813. 
A  reprint  of  an  article  in  the  same  journal  for  August  15.  1895. 

1897.  Ed.  Junta  de  Defensa  Contra  el  "Picudo/'  El  Progreso  de 
Mexico,  Vol.  V,  pp.  8-9,  Octobre  8. 

1897.  Ed.  El  Picudo  (Anthonomus  grandis  Boh.).  Documentos  ref- 
erentes  a  su  Existencia  en  Mexico  y  a  su  Invasion  in  los 
Estados  Unidos  del  Xorte.  Mexico,  Oficina  Tip.  de  la  Secre- 
taria  de  Fomento,  pp.  100,  figs.  1-5. 

Consists  of  a  few  letters  from  Mexican  cotton  planters  and  translations  of 
some  of  the  publications  of  the  Division  of  Entomology. 

1897.  Baeestrier,  L.  de. — Las  Medias  precautorias  contra  las  Plagas 
que  asolan  a  la  Agricultural.    El  Progreso  de  Mexico,  Vol.  IV, 
pp.  575-576,  May  '22. 
The  author  urges  the  necessitv  of  some  definite  action, 


1  L5 

L897.  Howard,  L.  O.— The  Mexican  Cotton-boll  Weevil  in  L897.  Cir- 
cular l>i\.   Ent.,  r.  8.  Dept.  Agric,   No.  27  (second  Beries), 

pp.  7. 

L897.   Il«>\\  lrd,  L.  0.— Insects  Affecting  the  Cotton  Plant     Farmers' 
Bulletin,  U.  S,  Dept.  Agriculture,  No.  L7,  pp.  L6  -':;.  ftgs.  ~  LI. 
Reprinted  From  Bulletin  88,  Office  of  Experimenl  Stations,  CJ.  S.  Dept. 
Agric,  pp.  81 1  850. 

L898.   ll"\\  \i;i>,  L.  0.— Remedial  Work  against   the  Mexican  Cotton- 
boll  Weevil.     Circular  Div.  Ent.,  CJ.  8.  Dept.  Agric,  N< 
(second  series),  pp.  6. 
This  is  supplementary  to  Circular  No,  87. 

L901.   Rangel,  A.  F. — Kstudios  preliminares  acerca  del   Picudo  del 

Algodon  {Insanthonomus  grandis  I.  C.  C).     Boletin   de   La 

Comision   de   Parasitologia   Agricola   r,   No.  3,    pp.  93-104, 

PI.  IX,  and  figure. 

Deals  with  45  experiments  regarding  destruction  by  means  of  hot  air,  hot 

water,  steam,  haplaphyton,  and  arsenic. 

L9G1,  Mally,  F.  W. — A  Preliminary  Report  of  Progress  of  an  Inves- 
tigation concerning  the  Life  History,  Habits,  Injuries,  and 
Methods  for  destroying  the  Mexican  Cotton-boll  Weevil 
(Anthonomous  (sic)  grandis).  Authorized  by  Special  Act  of 
the  twenty-sixth  Legislature  of  Texas,  pp.  1-30,  supplement 
pp.  35-45. 

1901.  Mally,  F.  W. — The  Mexican  Cotton-boll  Weevil.  Farmers' 
Bulletin,  U.  S.  Dept.  Agric,  No.  130,  pp.  30,  figs.  1-4. 

A  reprint,  with  minor  corrections,  of  the  preceding,  excepting  the  supple- 
ment. 

1001.  Raxgel,  A.  F. — Segundo  Informe  acerca  del  Picudo  del  Algo- 
don {Insanthonomus  (/rand is  I.  C.  Cu.).  Boletin  de  la 
Comision  de  Parasitologia  Agricola,  I,  Xo.  5,  pp.  171—1 7*'». 

1901.  Raxgel,  A.  F. — Cuarto  Informe  acerca  del  Picudo  del  Algodon 

(Insanthonom  us  grandis  I.  C.  Cu. ).     Boletin  de  la  Comision  de 
Parasitologia  Agricola,  I,  No.  7,  pp.  245-261,  Pis.  XVI,  XXIII. 

1902.  IIudsox,    E.    II.— The    Mexican    Boll    Weevil    (Anflwnomus 

grandis).     Farm  and  Ranch  (Texas),  Feb.  1,  1902,  p.  13,  figs. 

1902.  Hunter,  W.  I). — The  Present  status  of  the  Mexican  Cotton- 
boll  Weevil  in  the  United  States.  Yearbook  U.  S.  Dept. 
Agric.  1901,  pp.  369-380,  1  dg. 

1902.  Mally,  F.  W.— Report  on  the  Boll  Weevil.    Pp.    70,   figs.   3. 

Austin,  State  Printer. 

1903.  HUNTER,  W.  D.— Methods  of  Controlling  the  Boll  Weevil  (ad- 

vice based  on  the  work  of  1902).     Farmers'  Bull.  U.  S.  Dept. 
Agric.  Xo.  1G3,  pp.  1G,  figs.  2.   January. 


11(5 

L903.  Sanderson,  E.  D.— The  Mexican  Boll  Weevil.  Circ.  1,  Ent. 
Dept.  rlV.\.  Agric.  Exp.  Sta.  Press  Notes,  Vol.  V,  No.  3,  pp. 
8,  figs.  4.     February. 

1003.  Kill  the  Boll  Weevil.  How  to  Grow  Cotton  in  the  Weevil  Dis- 
trict. History  of  the  Pest,  its  Habits,  and  the  Remedies 
Plainly  Disclosed.  Pp.  8,  figs.  1.  Published  by  the  Executive 
Committee  of  the  Texas  Boll  Weevil  Convention. 

1903.  Champion,  G.  C. — Biologia  Centrali-Americana,  Coleopt.,  Vol. 
IV,  pt.  4,  p.  186,  PI.  XI,  figs.  3,  3a.     April. 

1903.  Save  the  Cotton  Crop.  Testimony  of  Cotton  Growers  on  Boll 
Weevil.  How  to  Insure  the  Cotton  Crop  in  the  Weevil 
District.  Pp.  16;  published  by  the  Executive  Committee  of 
the  Texas  Boll  Weevil  Convention,  Bull.  Xo.  2,  May.  Also 
published  in  German  under  the  title,  "Rettet  die  Baumwolle," 
and  in  Bohemian  under  the  title,  "Zachrante  bavlnu." 

1903.  Sanderson,  E.  D. — How  to  Combat  the  Mexican  Cotton-boll 
Weevil  in  Summer  and  Fall.  Circ.  1,  Ent.  Dept.  Tex.  Agric. 
Exp.  Sta.     Press  Xotes,  Vol.  V,  Xo.  1,  pp.  4.     August  10. 

1903.  Improved  Cotton  Seed  for  Texas  Planting.  Published  by  the 
Executive  Committee  of  the  Texas  Boll  Weevil  Convention, 
pp.  32.     Bull.  4,  Xov.  9;  revised  Xov.  17. 

1903.  Morgan,  H.  A. — The  Mexican  Cotton-boll  Weevil.  Circular 
Xo.  1,  La.  Agric.  Exp.  Sta.,  pp.  10,  figs.  3,  map  1.     Xovember. 

1903.  Wilson,  James. — Report  of  the  Secretary  of  Agriculture,  1903. 
Pp.  102-106  under  heading,  "Crisis  in  Cotton  Production," 
deals  with  the  Boll  Weevil  problem.     December. 

1903.  Connell,  J.  H. — Proceedings  of  the  Second  Annual  Session 
Texas  Cotton  Growers'  Convention,  Dallas,  Tex.  Pp.  99; 
many  illustrations.     December. 

190£.  Hunter,  W.  D. — Information  Concerning  the  Mexican  Cotton 
'boll  Weevil.     Farmers'  Bull.  Xo.  189,  if.  S.  Dept.  Agric.     Pp. 
1-31;  figs.  1-8.     February. 


O 


r 


k 


r 


